Functions provide an effective way to package and re-use program code, as already explained in 3. For example, suppose we find that we often want to read text from an HTML file.
This involves several steps: Read text from a file. It will return a string, and we can assign this to a variable, e. Each time we want to use this series of steps we only have to call the function. Using functions has the benefit of saving space in our program. More importantly, our choice of name for the function helps make the program readable. This naming helps to provide some "semantic interpretation" — it helps a reader of our program to see what the program "means".
Notice that the above function definition contains a string. The first string inside a function definition is called a docstring. Not only does it document the purpose of the function to someone reading the code, it is accessible to a programmer who has loaded the code from a file:.
We have seen that functions help to make our work reusable and readable. They also help make it reliable. When we re-use code that has already been developed and tested, we can be more confident that it handles a variety of cases correctly. We also remove the risk that we forget some important step, or introduce a bug. The program that calls our function also has increased reliability. The author of that program is dealing with a shorter program, and its components behave transparently.
To summarize, as its name suggests, a function captures functionality. It is a segment of code that can be given a meaningful name and which performs a well-defined task.
Functions allow us to abstract away from the details, to see a bigger picture, and to program more effectively. The rest of this section takes a closer look at functions, exploring the mechanics and discussing ways to make your programs easier to read.
We first define the function to take two parameters, msg and num. Then we call the function and pass it two arguments, monty and 3 ; these arguments fill the "placeholders" provided by the parameters and provide values for the occurrences of msg and num in the function body. A function usually communicates its results back to the calling program via the return statement, as we have just seen.
A Python function is not required to have a return statement. Some functions do their work as a side effect, printing a result, modifying a file, or updating the contents of a parameter to the function such functions are called "procedures" in some other programming languages.
Consider the following three sort functions. The third one is dangerous because a programmer could use it without realizing that it had modified its input. The same is true for functions. Python interprets function parameters as values this is known as call-by-value.
We begin by assigning an empty string to w and an empty list to p. After calling the function, w is unchanged, while p is changed:. Notice that w was not changed by the function.
Inside the function, the value of word was modified. However, that change did not propagate to w. This parameter passing is identical to the following sequence of assignments:. The function modifies properties , and this change is also reflected in the value of p as we saw.
The function also assigned a new value to properties the number 5 ; this did not modify the contents at that memory location, but created a new local variable. This behavior is just as if we had done the following sequence of assignments:.
Remember that you can use the id function and is operator to check your understanding of object identity after each statement. Function definitions create a new, local scope for variables. When you assign to a new variable inside the body of a function, the name is only defined within that function. The name is not visible outside the function, or in other functions. This behavior means you can choose variable names without being concerned about collisions with names used in your other function definitions.
When you refer to an existing name from within the body of a function, the Python interpreter first tries to resolve the name with respect to the names that are local to the function. If nothing is found, the interpreter checks if it is a global name within the module. Finally, if that does not succeed, the interpreter checks if the name is a Python built-in. This is the so-called LGB rule of name resolution: A function can enable access to a global variable using the global declaration.
However, this practice should be avoided as much as possible. Defining global variables inside a function introduces dependencies on context and limits the portability or reusability of the function. In general you should use parameters for function inputs and return values for function outputs. Python does not allow us to declare the type of a variable when we write a program, and this permits us to define functions that are flexible about the type of their arguments.
However, often we want to write programs for later use by others, and want to program in a defensive style, providing useful warnings when functions have not been invoked correctly. The author of the following tag function assumed that its argument would always be a string. The author of this function could take some extra steps to ensure that the word parameter of the tag function is a string.
This is a slight improvement, because the function is checking the type of the argument, and trying to return a "special", diagnostic value for the wrong input. However, it is also dangerous because the calling program may not detect that None is intended as a "special" value, and this diagnostic return value may then be propagated to other parts of the program with unpredictable consequences.
This approach also fails if the word is a Unicode string, which has type unicode , not str. If the assert statement fails, it will produce an error that cannot be ignored, since it halts program execution. Additionally, the error message is easy to interpret. Adding assertions to a program helps you find logical errors, and is a kind of defensive programming. A more fundamental approach is to document the parameters to each function using docstrings as described later in this section.
Well-structured programs usually make extensive use of functions. When a block of program code grows longer than lines, it is a great help to readability if the code is broken up into one or more functions, each one having a clear purpose. This is analogous to the way a good essay is divided into paragraphs, each expressing one main idea. Functions provide an important kind of abstraction. They allow us to group multiple actions into a single, complex action, and associate a name with it.
Compare this with the way we combine the actions of go and bring back into a single more complex action fetch. When we use functions, the main program can be written at a higher level of abstraction, making its structure transparent, e. Appropriate use of functions makes programs more readable and maintainable. It updates the contents of a frequency distribution that is passed in as a parameter, and it also prints a list of the n most frequent words.
This function has a number of problems. The function has two side-effects: The function would be easier to understand and to reuse elsewhere if we initialize the FreqDist object inside the function in the same place it is populated , and if we moved the selection and display of results to the calling program.
Given that its task is to identify frequent words, it should probably just return a list, not the whole frequency distribution. If we have done a good job at decomposing our program into functions, then it should be easy to describe the purpose of each function in plain language, and provide this in the docstring at the top of the function definition. This statement should not explain how the functionality is implemented; in fact it should be possible to re-implement the function using a different method without changing this statement.
For the simplest functions, a one-line docstring is usually adequate see 4. You should provide a triple-quoted string containing a complete sentence on a single line. For non-trivial functions, you should still provide a one sentence summary on the first line, since many docstring processing tools index this string. This should be followed by a blank line, then a more detailed description of the functionality see http: Docstrings can include a doctest block , illustrating the use of the function and the expected output.
Docstrings should document the type of each parameter to the function, and the return type. At a minimum, that can be done in plain text. This format can be automatically converted into richly structured API documentation see http: Illustration of a complete docstring, consisting of a one-line summary, a more detailed explanation, a doctest example, and Sphinx markup specifying the parameters, types, return type, and exceptions. This section discusses more advanced features, which you may prefer to skip on the first time through this chapter.
So far the arguments we have passed into functions have been simple objects like strings, or structured objects like lists. Python also lets us pass a function as an argument to another function. Now we can abstract out the operation, and apply a different operation on the same data. Notice that parentheses are only used after a function name if we are invoking the function; when we are simply treating the function as an object these are omitted.
Python provides us with one more way to define functions as arguments to other functions, so-called lambda expressions. We can equivalently write the following:. Our next example illustrates passing a function to the sorted function. When we call the latter with a single argument the list to be sorted , it uses the built-in comparison function cmp. However, we can supply our own sort function, e. These functions start by initializing some storage, and iterate over input to build it up, before returning some final object a large structure or aggregated result.
A standard way to do this is to initialize an empty list, accumulate the material, then return the list, as shown in function search1 in 4. Accumulating Output into a List. The function search2 is a generator. The first time this function is called, it gets as far as the yield statement and pauses. The calling program gets the first word and does any necessary processing.
Once the calling program is ready for another word, execution of the function is continued from where it stopped, until the next time it encounters a yield statement. This approach is typically more efficient, as the function only generates the data as it is required by the calling program, and does not need to allocate additional memory to store the output cf. In order to force the permutations function to generate all its output, we wrap it with a call to list.
The permutations function uses a technique called recursion, discussed below in 4. The ability to generate permutations of a set of words is useful for creating data to test a grammar 8. Python provides some higher-order functions that are standard features of functional programming languages such as Haskell. We illustrate them here, alongside the equivalent expression using list comprehensions.
We use this function as the first parameter of filter , which applies the function to each item in the sequence contained in its second parameter, and only retains the items for which the function returns True.
Another higher-order function is map , which applies a function to every item in a sequence. Here is a simple way to find the average length of a sentence in the news section of the Brown Corpus, followed by an equivalent version with list comprehension calculation:. We can also provide a lambda expression. The solutions based on list comprehensions are usually more readable than the solutions based on higher-order functions, and we have favored the former approach throughout this book.
When there are a lot of parameters it is easy to get confused about the correct order. Instead we can refer to parameters by name, and even assign them a default value just in case one was not provided by the calling program. Now the parameters can be specified in any order, and can be omitted. These are called keyword arguments. If we mix these two kinds of parameters, then we must ensure that the unnamed parameters precede the named ones.
It has to be this way, since unnamed parameters are defined by position. Dictionaries will be presented in 3. A side-effect of having named arguments is that they permit optionality. Thus we can leave out any arguments where we are happy with the default value: Another common use of optional arguments is to permit a flag.
Take care not to use a mutable object as the default value of a parameter. A series of calls to the function will use the same object, sometimes with bizarre results as we will see in the discussion of debugging below. If your program will work with a lot of files, it is a good idea to close any open files once they are no longer required. Python will close open files automatically if you use the with statement:. Programming is a skill that is acquired over several years of experience with a variety of programming languages and tasks.
Key high-level abilities are algorithm design and its manifestation in structured programming. Key low-level abilities include familiarity with the syntactic constructs of the language, and knowledge of a variety of diagnostic methods for trouble-shooting a program which does not exhibit the expected behavior.
This section describes the internal structure of a program module and how to organize a multi-module program. Then it describes various kinds of error that arise during program development, what you can do to fix them and, better still, to avoid them in the first place.
The purpose of a program module is to bring logically-related definitions and functions together in order to facilitate re-use and abstraction. Python modules are nothing more than individual. For example, if you were working with a particular corpus format, the functions to read and write the format could be kept together. If the format was updated, you would know that only one file needed to be changed. Similarly, a module could contain code for creating and manipulating a particular data structure such as syntax trees, or code for performing a particular processing task such as plotting corpus statistics.
When you start writing Python modules, it helps to have some examples to emulate. This returns the location of the compiled. The file that you will need to open is the corresponding. Alternatively, you can view the latest version of this module on the web at http: Like every other NLTK module, distance.
Since the code is distributed, it also includes the URL where the code is available, a copyright statement, and license information.
Next is the module-level docstring, a triple-quoted multiline string containing information about the module that will be printed when someone types help nltk. After this comes all the import statements required for the module, then any global variables, followed by a series of function definitions that make up most of the module. Other modules define "classes," the main building block of object-oriented programming, which falls outside the scope of this book. Most NLTK modules also include a demo function which can be used to see examples of the module in use.
Some module variables and functions are only used within the module. These should have names beginning with an underscore, e. If another module imports this one, using the idiom: You can optionally list the externally accessible names of a module using a special built-in variable like this: Some programs bring together a diverse range of tasks, such as loading data from a corpus, performing some analysis tasks on the data, then visualizing it.
We may already have stable modules that take care of loading data and producing visualizations. Our work might involve coding up the analysis task, and just invoking functions from the existing modules. This scenario is depicted in 4. Structure of a Multi-Module Program: By dividing our work into several modules and using import statements to access functions defined elsewhere, we can keep the individual modules simple and easy to maintain.
This approach will also result in a growing collection of modules, and make it possible for us to build sophisticated systems involving a hierarchy of modules. Designing such systems well is a complex software engineering task, and beyond the scope of this book.
Something as trivial as a mis-placed symbol might cause the program to behave very differently. We call these "bugs" because they are tiny in comparison to the damage they can cause. Sometimes, fixing one bug only reveals another, and we get the distinct impression that the bug is on the move. The only reassurance we have is that bugs are spontaneous and not the fault of the programmer.
Flippancy aside, debugging code is hard because there are so many ways for it to be faulty. Our understanding of the input data, the algorithm, or even the programming language, may be at fault.
First, the input data may contain some unexpected characters. For example, WordNet synset names have the form tree. However, this method broke when someone tried to look up the word PhD , which has the synset name ph. Although several people had tested the module before it was released, it was some weeks before someone detected the problem see http: Second, a supplied function might not behave as expected. What looked like a bug in the WordNet interface turned out to be a misunderstanding about WordNet itself: The only "bug" was a misunderstanding of the interface see http: It is easy to make the wrong assumption about the relative scope of two operators.
This is because the percent operator has higher precedence than the comma operator. The fix is to add parentheses in order to force the required scope.
As another example, suppose we are defining a function to collect all tokens of a text having a given length. The function has parameters for the text and the word length, and an extra parameter that allows the initial value of the result to be given as a parameter:.
However, it is created just once, at the time the Python interpreter loads the function. This one list object is used whenever no explicit value is provided to the function. Since most code errors result from the programmer making incorrect assumptions, the first thing to do when you detect a bug is to check your assumptions. Localize the problem by adding print statements to the program, showing the value of important variables, and showing how far the program has progressed.
If the program produced an "exception" — a run-time error — the interpreter will print a stack trace , pinpointing the location of program execution at the time of the error. If the program depends on input data, try to reduce this to the smallest size while still producing the error.
Once you have localized the problem to a particular function, or to a line of code, you need to work out what is going wrong. It is often helpful to recreate the situation using the interactive command line. Define some variables then copy-paste the offending line of code into the session and see what happens.
Check your understanding of the code by reading some documentation, and examining other code samples that purport to do the same thing that you are trying to do. Try explaining your code to someone else, in case they can see where things are going wrong. Python provides a debugger which allows you to monitor the execution of your program, specify line numbers where execution will stop i.
You can invoke the debugger on your code as follows:. It will present you with a prompt Pdb where you can type instructions to the debugger.
Type help to see the full list of commands. Typing step or just s will execute the current line and stop. If the current line calls a function, it will enter the function and stop at the first line. Typing next or just n is similar, but it stops execution at the next line in the current function. The break or b command can be used to create or list breakpoints.
Type continue or c to continue execution as far as the next breakpoint. Type the name of any variable to inspect its value. Remember that the problem arose the second time the function was called. Here we typed just two commands into the debugger: The debugger has helped us to localize the problem, prompting us to check our understanding of Python functions.
In order to avoid some of the pain of debugging, it helps to adopt some defensive programming habits. Instead of writing a line program then testing it, build the program bottom-up out of small pieces that are known to work.
Each time you combine these pieces to make a larger unit, test it carefully to see that it works as expected. Consider adding assert statements to your code, specifying properties of a variable, e.
Sample error reflects the risk that, purely by chance, a randomly chosen sample of opinions does not reflect the true views of the population. A thousand interviews is a large enough sample for many purposes and Mr Gallup is reported to have conducted 3, interviews.
The answer is that sampling error has a far more dangerous friend: George Gallup took pains to find an unbiased sample because he knew that was far more important than finding a big one.
The Literary Digest, in its quest for a bigger data set, fumbled the question of a biased sample. It mailed out forms to people on a list it had compiled from automobile registrations and telephone directories — a sample that, at least in , was disproportionately prosperous.
To compound the problem, Landon supporters turned out to be more likely to mail back their answers. All that gave them for their pains was a very precise estimate of the wrong answer. The big data craze threatens to be The Literary Digest all over again. Returning officers do not estimate an election result with a representative tally: An example is Twitter.
It is in principle possible to record and analyse every message on Twitter and use it to draw conclusions about the public mood. But while we can look at all the tweets, Twitter users are not representative of the population as a whole. According to the Pew Research Internet Project, in , US-based Twitter users were disproportionately young, urban or suburban, and black. There must always be a question about who and what is missing, especially with a messy pile of found data.
Kaiser Fung, a data analyst and author of Numbersense , warns against simply assuming we have everything that matters. As citizens of Boston download the app and drive around, their phones automatically notify City Hall of the need to repair the road surface. Solving the technical challenges involved has produced, rather beautifully, an informative data exhaust that addresses a problem in a way that would have been inconceivable a few years ago.
Yet what Street Bump really produces, left to its own devices, is a map of potholes that systematically favours young, affluent areas where more people own smartphones. That is not the same thing as recording every pothole.
As Microsoft researcher Kate Crawford points out, found data contain systematic biases and it takes careful thought to spot and correct for those biases. Who cares about causation or sampling bias, though, when there is money to be made? Corporations around the world must be salivating as they contemplate the uncanny success of the US discount department store Target, as famously reported by Charles Duhigg in The New York Times in Duhigg explained that Target has collected so much data on its customers, and is so skilled at analysing that data, that its insight into consumers can seem like magic.
The manager apologised profusely and later called to apologise again — only to be told that the teenager was indeed pregnant. Target, after analysing her purchases of unscented wipes and magnesium supplements, had. This is vanishingly unlikely. We should not buy the idea that Target employs mind-readers before considering how many misses attend each hit.
Fung has another explanation: None of this suggests that such data analysis is worthless: Even a modest increase in the accuracy of targeted special offers would be a prize worth winning. But profitability should not be conflated with omniscience. The paper became famous as a provocative diagnosis of a serious issue. It is routine, when examining a pattern in data, to ask whether such a pattern might have emerged by chance.
The standard of these courses is quite unknown because the university refuses to disclose any of its teaching materials. So on Mondays and Thursdays for example the students must believe that response increases with dose, but on Tuesdays and Fridays they are called upon to believe that response decreases with dose. What he does not say is how this absurd conflict is resolved, or how it can be made compatible with science or simple common sense.
The course evidently teaches you how to believe several mutually contradictory things at the same time, or at least on alternating days. Not only are some of the doctrines of CAM incompatible with science or common sense, but they are often also incompatible with each other. Homeopaths subscribe to the bizarre doctrine that the less you give the bigger the effect, but herbalists do not.
Herbal medicine is nothing other than pharmacology, albeit pharmacology as practised at the beginning of the 20th century, before biological standardisation was introduced to assure constant potency of medicines. Nutritional therapists go to the opposite extreme and want to give huge and sometimes toxic doses.
Likewise, students of reflexology are taught that a small area on the big toe is connected with the pituitary gland. Not only is this incompatible with physiology, but it is also incompatible with homeopathy, herbal medicine and nutritional therapy. The department of complementary therapies seems to resemble a collection of religious sects at war with each other, rather than anything recognisable as science.
Homeopathy students get one course out of 22 called "Methods of Research in Complementary Medicine", and a project, "Research in Practice". It is impossible to know what is taught on these courses because the university refuses to release any of the course materials. But I find it hard to imagine that the courses are very critical when the official response from the university cited the Spence study as though it provided evidence for the efficacy of homeopathy.
The day after the Nature commentary, the University of Westminster issued a statement in response. Well, since the University has so far refused to release any of the documents, it is hard to judge what that validation is worth. The validation documents will, no doubt, appear eventually. One mechanism that is intended to maintain the standard of degrees is the external examiner.
Their identities, like almost everything else, are kept secret. In the case of the Westminster BSc in homeopathy, however, we are in luck. Since April , that has been Andy Kirk RSHom , a homeopath in private practice, with no degree and no scientific qualifications. He, I imagine, is not likely to question the bizarre homeopathic doctrine that the smaller the dose you give, the bigger effect you get. Correction 4 April It seems that Westminster supplied wrong information to the TQI site, and the external examiner is not Kirk.
They refuse to say who it is. But watch this space. The Society of Homeopaths is an organisation for homeopaths who have no medical qualification. Their scientific credentials can be judged from this quotation from their web site. This is pure gobbledygook. The word "energy" is being used in a way unknown to science.
The study to which they allude here has to be the worst paper ever published. It is the infamous Spence study, which is dealt with below. Oddly enough, this paper is one that Westminster students were asked to assess critically. The fact that this is the best evidence that the University can produce in response to criticisms is, perhaps, the best reason ever to think that the material being taught is not, in any sense, science, and is not appropriate for a BSc. It seems that they are hoist by their own petard.
Nature March 22 ran this commentary , alongside a News item by Jim Giles:. Here is some of the coverage of this commentary more soon, including some of the abuse. A transcript pf the podcast is here. There was helpful intervention from Michael Marmot who had talked, in the first half of the programme, about his longitudinal population studies. Dr Fisher, who is clinical director of the Royal London Homeopathic Hospital, made a very interesting comment, at the end of a discussion about whether homeopathy was a suitable subject for a science degree.
To that extent I would agree with Professor Colquhoun. I presume this refers to the Cochrane review "Homoeopathic Oscillococcinum for preventing and treating influenza and influenza-like syndromes". What this actually says is. However, taking homoeopathic Oscillococcinum once you have influenza might shorten the illness, but more research is needed. Well, it might , but even if it did, the average length of the putative "shortening" of the illness was a mere 0.
To call that "effective" seems to me to be just a tiny bit of an exaggeration. I love that title: But her piece is followed by a flood of comments, almost all of them thoroughly sensible. Why not Levitation alongside Aeronautical Engineering? Thanks to everyone who sent letters of support, not least the regular scientists from Westminster, and University of Central Lancashire who are clearly rather embarrassed by their homeopathic colleagues.
Inevitably there were a few bits of hate mail too, each answered politely, and some even resulting in a degree of agreement. The only one worth quoting is a rather mild one from George Lewith see below.
I have yet to find that this particular course from personal experience involves a single piece of science. You might like to investigate at the Bartlett. I guess one of us is out of sync anyway. Unlike George it appears , I know little about architecture, but the idea of design for a tower block based on homeopathic principles sounds a bit scary to me. The second week in March was a champion. Two different nutrition stories hit the headlines, both misreported and neither very informative.
More fish oil below and the alleged benefits of grape juice. The inimitable Ben Goldacre has dealt with yet another story about the miraculous effects of omega Read it on badscience.
The media were full of utterly uncritical reports of a programme that was to be broadcast by Channel 5 TV.
The report in the Times was particularly uncritical. But the "study" was on only four very untypically heavy children, it had no control group, and it did not measure behaviour or exam performance, but rather a chemical in the brain.
He has published quite a lot in this area. Dr Alex Richardson Oxford , who has worked a lot with Prof Puri, has dissociated herself from this study. E and tiredness" at the Inner Potential Centre. Why is it that we discover only from Ben Goldacre that Professor Puri seems to have something of a vested interest in the outcome of his studies? He is the registered inventor on patent GB , for "Formulation comprising eicosapentanoic acid or an ester thereof and a triterpene or an ester therof".
The Channel 5 TV programme in which this work was featured was mysteriously cancelled at the last moment. Following a press release from the University of Glasgow, news media round the world carried the story that grape juice could prolong your life more than any other sort of fruit juice.
David Rose in The Times: Jeremy Laurence in the Independent "Why a glass of grape may be best way to start your day". But the study to which these reports refer did not measure any health benefits whatsoever. Marks and Alan Crozier. It was an exercise in analytical chemistry. Of course the sponsorship does not mean there is anything wrong with the results, but declaration of financial is now considered to be very important.
But does this really mean better health? The anti-oxidant story, after all, has been pretty thoroughly discredited some time ago though it is still live and well in the advertisements of the supplements industry. The Kame project was a prospective study over 10 years on Japanese Americans. It was not randomised: For example, corrections were made for years of education, smoking status, tea-drinking frequency, regular physical activity and total fat intake. Such corrections are fallible, and of course there is no guarantee that all the possible relevant factors have been thought of.
Dr Dai, first author on the Kame project is careful to point out that the project gave no information on what sort juice of juice was drunk, and that it was not known what constituents of the juice produced the putative effects. He is quoted thus. The WCRF, incidentally, is not a conventional cancer researh organisation but is dedicated to the view that cancer can be prevented by changes in diet and lifestyle.
Many of its claims are unproven. Two of the comments that followed the debate were as follows. Space researchers do not, after all, waste time trying to disprove the beliefs of flat- earthists. Neither would it be helpful for a Nobel prizewinning chemist to stride into a church and denounce the holy water there as nothing more than H2O.
There is a very large and ever expanding array of alternative treatments, some more bizarre than others, which could tie up the resources of NICE for an indefinite period.
It is no concern of scientific medicine. Nobody is proposing to ban fairies or leprechauns. It would be both undesirable and impossible. I suspect infiltration of the Department of Health by little green men. This document is not just barmy, but positively dangerous. In the rebuttal of the programme on the FIH web site, they claim that they do not promote alternative medicine, but elsewhere on the site they state their aim as "makes safe and effective complementary therapies available to patients in conjunction with conventional healthcare".
The MHRA recently, for the first time, betrayed its brief to nake sure that medicines work and are safe. This action has been condemned by just about every professional organisation. Nobody knows exactly what caused them to lose their heads in this way, but it is clear that they were under pressure from both the Department of Health and from the Prince of Wales.
The Department of Health is clearly sympathetic to quackery, as shown by the letter below , and by their refusal to allow alternative medicine to be referred to NICE for assessment. The letter alleged a breach of confidence by Ernst. Having been sent a draft of the Smallwood report, Ernst was so horrified by the scientific standards in that document, he felt obliged, in the public interest, to speak out about it. Ernst was contacted by a newspaper, which had a copy of the draft, and described the initial findings as "outrageous and deeply flawed".
Prof Ernst was doing exactly what academics are meant to do. For a Prince, in a constitutional monarchy, to put pressure on a university to silence a conspicuously honest academic is just not acceptable. The Prince of Wales behaviour was bad enough, but, to be generous, he is perhaps, a well-meaning but poorly educated man, filling in his time as best he can.
Instead of supporting his staff, and supporting academic freedom, he appeared to cower before the Clarence House letterhead. After keeping Prof Ernst on tenterhooks for an entire year he eventually deigned not to fire him in the most grudging and unpleasant way imaginable.
It was shown on the TV programme, and is reproduced below. They are worth reading because the advice comes from Catherine Collins, a real dietician, not a nutribollocks guru. The aim was to analyze the effects of antioxidant supplements beta carotene, vitamins A and E, vitamin C [ascorbic acid], and selenium on deaths from any cause in adults. The analysis seems to have been done well, and the results are startling.
In 47 low-bias trials with participants, beta carotene increased death rates by 7 per cent, vitamin A by 16 per cent, and vitamin E by 4 per cent when taken separately.
Vitamin C gave contradictory results and selenium showed no detectable effect. This work got an excellent write-up in The Times , by their health correspondent, Nigel Hawkes. Luckily, this was neutralised by a second piece on the same page by Nigel Hawkes, "Phooey.
Sensible balanced diet is the best investment":. This book sets out dramatically the harm, sometimes serious harm, that untested "supplements" have done to some individuals. The supplements industry puts the Prince of Wales in the shade when it comes to subverting common sense and good science. Needless to say, the supplements industry has already organised vilification of this excellent bit of work.
Dr Ann Walker, immediately tried to discredit the study, saying "The results of these mixed-sample metaanalyses are worthless" The Times. The editorial concludes "Although still considered to be controversial by some, taking a daily multinutrient supplement would bridge the gap between intake and requirements and ensure that nutrient target intakes are met.
No mention at all of her role as spokesperson for the Supplements industry. Needless to say, supplement salesman Patrick Holford has weighed into the vilification. His objections have been dealt with nicely on the cutely named web site stopholfordtalkingrubbish.
Find the answers here. Holford is the man who, in the BMJ said "Competing interests: Holford himself has said. They say "we only supply supplements, foods and drinks that are recommended by nutrition expert, Patrick Holford. Another interesting recent paper has appeared in Archives of Internal Medicine. Garlic is widely promoted as a cholesterol-lowering agent, but the evidence so far has been lousy. During the tear-wrenching death of Mimi in the last act, it occurred to me that if we had taken advice from homeopaths and the like, people would still be dying young from tuberculosis.
For me, Verdi beats even Puccini with the pathos and drama of the death of Violetta from consumption in La Traviata. La Traviata appeared in , and at that time the cause of tuberculosis was not known. It is often said that homeopathy, and some other forms of quackery, though not effective, are at least harmless.
This history shows otherwise. Sugar pills do not, of course, poison your body. They poison your mind. Belief in their crude and irrational delusions inhibits search for the real causes of disease and for real cures. Like creationists , homeopathists and their ilk take the lazy approach. If we had listened to them, people would still be dying of tuberculosis and cholera.
This is not just historical either. Why, I wonder, does quackery seem to have become rife in Scotland. I have already written below about homeopathy and aromatherapy in Edinburgh. A Dalkeith GP made a big mistake when he prescribed homeopathiv belladonna for the feverish son of one of my colleagues! Now a more systematic account has appeared in the British Journal of Clinical Pharmacology , which has just published a disturbing paper, Homoeopathic and herbal prescribing in general practice in Scotland, Sarah Ross, Colin R.
Four thousand one hundred and sixty patients 2. Three hundred and sixty-one patients 0. Patients prescribed a homoeopathic or herbal remedy were also prescribed a median of four and five conventional medicines, respectively. Our study reports that a substantial number of Scottish general practitioners prescribe homoeopathic and herbal remedies, with an approximate doubling in the number of children prescribed homoeopathic remedies. The majority of patients prescribed homoeopathy were female, with a median age of 48, possibly reflecting the gender split of patients attending their GP rather than any gender bias , although available data suggest that women between the ages of 35 and 60 are the main consumers of over-the-counter remedies or consulters of CAM practitioners .
And just look at this bit of wishful thinking from the Highland NHS complete with personal testimonials, just like every snake-oil advertisement.
In the Independent , 20 Feb, , Thomas Sutcliffe writes thus. Here is a very odd looking cover for an academic brochure. It is the brochure for the Institute of Optimum Nutrition.
In between the advertisements it describes a number of course that sound quite academic. The give-away is the term Nutritional Therapy. The brochure claims that it offers. This Institute is run by the totally unqualified Patrick Holford, whose prententions have been analysed so effectively by Ben Goldacre.
See the details on badscience,net: How on earth can an outfit like this be accredited by a university? What on earth is the University of Bedfordshire formerly Luton thinking of? Not much, one suspects. This is just brilliant. The Advertising Standards authority have stopped the foromost purveyor of nutribollocks from using her phoney PhD to lend an air of verisimulutude to her otherwise bald and unconvincing narratives.
Whoever it was, they deserve a medal. It is high time science fought back actively against the tide of rubbish that engulfs us. The print edition of the Guardian gave this story a magnificent spread right , under the heading A Menace to Science.
Also an excellent article by Marina Hyde, Shamelessness: Never mind the truth: For a bit of light amusement, I decided to publish the occasional bit ot email correspondence. This one arrived on 9th Feb This is as true of sore throats and ear infections in small children as it is to asthma and Rheumatoid Arthritis in adults.
You really should do more research before shouting your mouth off over things you clearly know nothing about. I think that you have hit the nail on the head, If you can produce the numbers to show that what you say is true, then I and everyone else I know will believe you it would, of course, have to be done by comparison with an appropriate control group. The problem is that the homeopathic community have had years to produce the evidence, and so far it has not been forthcoming. I suppose it is true to say that the evidence would have to be good in view of the inherent implausibility of homeopathy.
If it turned out that it was possible to produce an effect with no molecules present, the whole of present day chemistry and physics would be overturned and since it seems to work rather well that would be surprising. Homoeopathy may sound implausible, I agree, it does if you only look at modern so called science.
There are plenty of things in life which are unexplained, such as love I am sure and hope that you must have felt it? You are right so far in that to convince people they need proof. However, for most of us as Homoeopaths, our proof is that our patients get well, and they do, most of the time.
That is generally enough proof for our patients too, especially when their brain tumours disappear. Of course there will always be some placebo effect in some people as in medicine of any sort. Perhaps you should try it for yourself and FEEL the proof Oh and by the way I think that present day physics and chemistry beliefs need overturning, desperately. Thanks for those comments. I see that you really do appreciate the need to produce evidence if you are to convince people, however convinced you may be yourself.
Your most intriguing comment, though, was " I think that present day physics and chemistry beliefs need overturning, desperately". They are all products of the application of chemistry and physics and years ago they would have seemed miraculous. On the face of it, that sounds pretty dangerous, even by his standards.
A bit of investigation shows that the report is based on some perfectly good scientific work on antimicrobial properties of essential oils by Peter Warn. Now we have to contend not only with inaccurate journalists but also with University publicists who insist on talking before there is anything to say.
Journalists seem incapable of understanding the meaning of these words, and the result is irresponsible reports though one might detect a hint of irony in the picture that the BBC used to illustrate acupuncture; right.
There is nothing new in the failure of journalists to distinguish good science from junk. In the case of Durham the effect is to use public money to produce bad evidence that can be used to promote the dubious claims of a private company, in the case "Eye Q" pills made by Equazen. Nothing there about seeing whether the treatments work! But Peter Hain seems to think he knows the answer already.
He was "delighted that Northern Ireland is leading the way in integrating complementary and alternative therapies into the National Health Service". Peter Hain used to be something of a hero to me. In the 70s his work for the Anti-apartheid movement was an inspiration see his autobiographical notes. Now he has sunk to promoting junk science. On his web site he had a section on this topic.
Later, he developed asthma too. At first, we relied on conventional treatments. Various creams were prescribed, and a steroidal spray. In fact, the spray seemed to make him more dependent. So instead, we turned to complementary medicine. You changed diet and gave homeopathic sugar pills.
And that is a reason for the taxpayer to fund homeopathy? Any fool can see that this anecdote means that either a change in diet helped, b homeopathy helped, or c the eczema would have got better anyway.
They "grow out" of it. And guess who supports it? The Prince of Quacks , once again exerting his unconstitutional influence on public policy. The report tells us nothing whatsoever about the effectiveness of the treatments, because the "pilot" study was not designed to do so.
It is 40 pages of waffle. The report also says "Get Well UK is a not for profit organisation established in response to a recommendation by the House of Lords in that complementary therapies should be made available through the NHS. This is a gross misrepresentation of the House of Lords report which said this should be done ONLY if the treatments worked better than placebo. And, with very few exceptions, that still remains to be shown. At the end of the "pilot scheme" there will have been no proper assessment of the effectiveness of the treatments.
We shall be none the wiser. The story was spotted by the Radio 4 consumer programme You and Yours. On Monday 5 February they broadcast the story. Other contributors included Stephen Senn , the distinguished medical statistician. It seems that television journalists and lawyers have been a great deal more effective in unearthing the evidence than the regulatory authorities or the police.
The MHRA has been working on the case for three years and has still not produced its report. Read the transcript here. Since the deregulation of industry that started around with Ronald Reagan and Margaret Thatcher, one has become accustomed to dishonesty by big business. But academics are involved too. GSK organised three large scale clinical trials of Seroxat on children with depression, in the hope of getting Seroxat licensed for this use.
It is these trials that have given rise to the charge that GSK tried to suppress evidence that Seroxat caused an increase risk of suicide in young people. Martin Keller is chair of psychiatry at Brown University. The evidence found by Panorama also shows that his reputation seems to be for hire. His university home page shows that he holds many influential politicians.
It does not mention that in one year he got half a million dollars from drug companies including GSK. In another mail from the ghost writer to Dr Keller says that all the necessary materials are enclosed so that he can submit study for publication, even down to the covering letter which says: Revise if you wish.
Perhaps Keller at least checked the results carefully? But it seems not. This is what another of its PR people wrote when asked if the journal article would be publicised. Brown University does not appear to have learned the lesson. The news section on their web site boasts of this ghost written work.
The amazing decision of the Prescription Pricing Authority to allow the NHS to pay for magnetic bandages has been covered in detail here part 1 , part 2 , part 3 , as has the extreme reluctance of the PPA and the Department of Health to give any useful information here , and here. More on this topic elsewhere. Eventually the decision was referred to the Office of Fair Trading has delivered its judgement.
MagnoPulse Limited was told to remove most of its absurd claims from its advertising. The Vanessa Feltz show The highlight of the show was a 10 minute debate between Les Rose see also below and a homeopath, Katherine Armitage. Peter Fisher said "it is true that there is not as much evidence as you would like" for the efficacy of homeopathy.
Hear it in his own words. Peter Fisher speaks [ mp3 file ]. Of course he went on to insist that it was not all placebo effect. For more on Peter Fisher, see here, and here , and here.
This, from someone whose knowledge of physics is clearly next to zero! Katherine Armitage , incidentally is connected with an organisation called innerpotential. Their activities are not limited to the usual battiness of homeopathy and acupuncture. They are much more ambitious. This would be laughable if people were not parting with hard-earned money for false promises. It breaks my heart to see people getting rich on this stuff, when my university is full of young people, working very hard, for modest salaries, trying to discover something that is actually true.
For earlier episodes in this saga, see part 1 , part 2 , part 3 and part 4. Advice to consumers ". It includes the following passage. This wording is, to my mind, misleading and disgraceful. The Energetic Body is much more expansive than the physical body, though the physical body forms its core. Quantum Shiatsu developed into a system under the influence of Quantum Physics--in particular, the theory of relativity and quantum mechanics--and its relevance to human healing.
By applying quantum principles to shiatsu, contact with faster, more expansive energy became possible. This resulted in the inclusion of chakras as well as meridians into a shiatsu framework. The supply of this sort of stuff is almost endless.
Ben Goldacre has drawn my attention to another example that is seriously bonkers. Lynne McTaggart writes pseudo-scientific nonsense using language that sounds vaguely like physics - try here if you can stand it. Do these people really believe that the words they use have any meaning? Or is it all just a callous charade to make money. According to some estimates around half of US adults take antioxidant pills daily in the belief that they promote good health and stave off disease.
The trial was set to run for 6 years, but two-thirds of the way through the researchers pulled the plug after discovering, to their surprise and horror, that those taking supplements were doing worse than the controls. They had developed 28 per cent more cases of lung cancer, and their overall death rate was 17 per cent higher. Vitamin E shot to fame in the early s, after two large studies involving more than , people in total found that those with a diet high in vitamin E were significantly less likely to suffer cardiovascular disease.
Use of vitamin E supplements soared. In , almost nobody took vitamin E; by the end of the decade an estimated 23 million US citizens were knocking back daily doses. They may shorten your life. The MHRA has just betrayed the trust placed in it by the public by allowing untrue claims to be put on the labels of homeopathis and herbal treatments, apparently under pressure from the government and the Prince of Wales, as described below , and here.
The cause such outrage that the MHRA was censured by an annulment debate. In contrast, the main medical organisations have kept disgracefully silent. Nothing has been heard from the British Medical Association I hear that a move to say something was heavily defeated.
No evidence of effectiveness. The homeopaths, and the companies that produce over-the-counter homeopathic remedies, are understandably delighted. Well, you might say, so what? Most scientists would agree that the labelling is a joke, but in a world awash with ridiculous claims, why get worked up? The debate on "Does Homeopathy Work? The audience seemed to contain a large number of homeopaths.
He was sweetly reasonable and tried to explain the nature of evidence to an audience that was clearly not interested. The debate started with 30 minutes from Peter Fisher, clinical director of the Royal London Homeopathic Hospital, and homeopathic physician to the Queen more on Peter Fisher here and here. We were treated to half an hour of shameless cherry-picking of the evidence. This puzzles me, because Fisher is a medical doctor, and he unlike many homeopaths , is quite sound when it comes to the really dangerous aspects of homeopathy such as recommending homeopathic malaria prevention, and recommending against vaccination.
That is a lot more than can be said for Melanie Oxley from the Society of Homeopaths who was in the audience: Fisher rightly condemns such absurdities. He also is one of the few homeopaths who has published negative results for homeopathy. Despite all that, his discussion of the evidence was selective to the point of dishonesty. Somehow, I doubt that he intended to be dishonest: Which is quite true". He then went on to say that his gigabyte memory stick would, according to a chemist would be made almost entirely of silica with trace impurities of boron and phosphorus.
Yet it can hold a lot of information. What actually is so implausible about this? The possibilty that water actually stores information and then transmits it to the body. These comments betray such a basic misunderstanding of physical chemistry that I am lost for words. Do these words show a genuine inability to understand basic physics? Or are they a wilful distortion of physics designed to add an air of verisimilitude to an otherwise bald and unconvincing narrative? I confess that I have no idea.
For the real story on the memory of water, see below. It is a matter of perennial interest to know how many quacks are genuinely deluded, and how many are cynically in it for the money. Presumably the directors of big companies like Boots the Chemists or Holland and Barrett are in the latter category. One case that is undoubtedly a dishonest scam was unveiled in a very nice bit of investigative journalism by Paul Mason for the BBC2 Newsnight programme , on 1st December If the claim were true it would be headline news for the world.
He approached film actor Richard E Grant to front the scheme: There is not, of course, the slightest reason to think that goat serum cures anything. Newsnight gives some very interesting background on Mr Hart Jones.
Swaziland has about people with HIV, but only 15 are receiving anti-retroviral drugs. This appears to be a major criminal enterprise. You can read here some of the original documents that were unearthed by Newsnight. My pharmacological curiosity was stirred by a TV advertisement for a spray that, it was claimed, could stop you snoring.
In a further first for a snore remedy the results of the trial were published in Phytology Research, an international journal, in October This claim was not so easy to check because the manufacturer mis-spells both the name of the author and the name of the journal. The paper in question seems to be this.
Sadly this paper is not very convincing. For those who are interested, here are a few details. Snorers were randomly allocated to receive a metered dose of "Stop snoring "gargle, "Stop snoring " spray or placebo gargle there was no placebo spray at all. The paper makes no mention of what was used as placebo, but Dr Prichard tells me "The content of the placebo could not be an essential oil. I have been told by the manufacturer that we used a sugar type mix". Actually it contained water, sodium saccharin, polysorbate 20, potassium sorbate and citric acid.
It would be have been obvious tor the patient whether they got the placebo or not. Statistical analysis was performed using the Wilcoxon non-parametric test. The comparison that is made is before and after in each treatment group, rather than comparing the groups.
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