A problem of unstated data

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In The Guardian's ongoing series of science questions posed to major political parties, the Green Party's response to the question
Is animal testing necessary? Are the ethical concerns outweighed by the benefits? How would you like to see regulations on animal testing change under your government, if at all?
states that

We agree with the independent patient safely organisation, the Safer Medicines Trust, that animal testing may be more harmful than helpful.

The Safer Medicines Campaign, previously known as Europeans for Medical Progress, has a habit of using arguments like the following:

  1. Results from other species simply do not reliably translate to the clinic, as evidenced by the 92% failure rate of potential new drugs in clinical trials. [1]
  2. That must include animal data, since crucial decisions, such as whether to proceed to clinical trials and whether the drug might cause cancer or birth defects are based on demonstrated safety in animals. Yet, as we know from Northwick Park, even safety in monkeys at enormous doses does not guarantee safety in humans. [1]
  3. A large systematic survey published in November 2009 found serious omissions in reporting of data and in strategies to reduce bias in results. Only 12% of the animal studies used randomisation, only 14% used blinding and only 8% gave the raw data. [1]
  4. The best way to evaluate the effectiveness of animal tests for drug safety is to compare their results with subsequent real- world outcomes in patients and consumers. [1]
  5. Aids is another: while at least 80 vaccines work in animals, all 80 have failed in human trials. Similarly, every one of more than 150 stroke treatments successful in animals has failed in human testing. A study in the British Medical Journal found that animal tests accurately predict human response less than 50% of the time. [2]

[1] Safer Medicines Campaign Spring 2010 Newsletter http://www.safermedicines.org/newsletters/newsletter_spring_10.pdf
[2] "The dead end of animal research", Comment is Free (Guardian), August 2009 http://www.guardian.co.uk/commentisfree/2009/aug/07/animal-testing-medical-research

I've previously argued that their arguments are weak. Take the first. We're told 92% of the drugs tested that pass animal tests fail in later human clinical trials (the phrasing is mildly ambiguous but I believe that is what is meant). While that might look like a problematic figure, I would think that any competent scientist would also want to know:

  1. The proportion of drugs that failed animal tests but would pass a later human clinical trial.
  2. The proportion of drugs that failed animal tests but would also fail a later human clinical trial.
  3. The proportion of drugs overall that fail animal tests

In other words, we ideally want a test for drugs that perfectly predicts the results of human clinical trials, as we don't want to do clinical trials that needlessly endanger people or might unacceptably delay them getting the best treatment. In the event we don't have that, we need to know four numbers to get a good picture of things - how many drugs failing one test would fail the other (which is a good thing), how many would pass one but fail the other (which would mean we are maybe giving those in clinical trial dangerous substances), how many would fail one but pass the other (meaning we've missed out on a potential cure) and how many pass both (which again is a good thing - these are the drugs that will go into common usage).

Similarly, other quotes above give one piece of information without giving corresponding pieces of information that are crucial in assessing the best options in pharmaceutical testing, and I would argue that "The best way to evaluate the effectiveness of animal tests for drug safety" is not "to compare their results with subsequent real- world outcomes in patients and consumers" but "to compare their results with other potential testing techniques".

I'm continually disturbed by the fact that the Safer Medicines Trust, which says "We focus on evidence based analysis of animal experimentation to assess the balance of help or harm to human health", so frequently writes pieces of publicity that fail to give all the necessary information to do this.

If you think animal testing is morally wrong, that's not something I can really argue with you about, but if you want to make a case it's outdated and there are better options I'd love to hear about them, but I'm usually disappointed by how the case is presented.

The Science Vote

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Recently, Michael Brooks, a journalist and author with a background in quantum physics, announced he will stand against David Tredinnick in the Bosworth constituency in the general election. This is because David Tredinnick has such famously irrational beliefs.

This has caused some controversy, as it may split the vote and so on, and Brooks is not a man local to Bosworth.

On astrology

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I appear to have found myself engaged with @angelneptustar, an astrology fan and also a Boris Johnson fan.

This came about through Marsh's post at the Mersyside Skeptics site. I read through the HuffPo article in question (I refuse to link to that rag, but you can follow through to it if you really wish) where angelneptustar comments on Boris Johnson's astrology chart and how it shows he is very talented.

Not a blog post

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This is not a blog post. It is an instruction to anyone self-identifying as a skeptic to read this.

To Columbo's Rescue

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Browsing my arxiv feeds this morning, I picked up this post - "A defense of Columbo (and of the use of Bayesian inference in forensics): A multilevel introduction to probabilistic reasoning" by G. D'Agostini.

Considering the topic, it's an enjoyable read. It's motivated by this NewScientist article from late last year. I criticised that article myself but did not touch upon the incident with Columbo. D'Agostini provides a fairly clear if mildly technical explanation of the mathematics behind the problem expressed - of the strength of the evidence against the killer Columbo caught when he picked one of thirteen (or twelve, as the NewScientist article says, but that's a minor niggle) cameras off a shelf, taking the one involved in the crime. As NewScientist says:

If only it were that simple. Killer or not, anyone would have a 1 in 12 chance of picking the same camera at random. That kind of evidence would never stand up in court.

Pascal's Wager

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I've long held that Pascal's Wager is a completely absurd argument. Most people will know what Pascal's Wager is, but it's loosely speaking the argument that you should believe in God because doing so offers the possibility of infinite reward, whereas not doing so offers no reward at all.

There are obvious flaws in it, which apparently even Pascal recognised. The primary one I think, is that the reward for believing something does not lead to a mechanism by which you can genuinely accept that belief. If you offer me a £10,000,000 to believe that pigs can fly, I will not be able to start believing that pigs can fly just to gain a benefit.

For this obvious reason, if anyone mentions the Wager in any context other than an example of dubious logic, treat anything else they say with caution.

However, Pascal's Wager is not really the object of this post. What I'm going to discuss is instead (despite the blog title) Pascal's Mugging.

On the BHA's response - part 2

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The BHA have posted the final two parts of their response to the S&TC Evidence Check. As I covered the first parts (to a greater or lesser extent, I skipped one section entirely), I thought I should continue to look at the final two.

Paradoxes - The Meta-Newcomb Paradox

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It's nearly the weekend, and I need to give my colleagues something to keep their brains working while they're away from their desk. So...

It's been a week since you encountered Newcomb's Predictor. You, being a classic two-boxer personality, opted to take both boxes, and although mildly disappointed to find you won only £10,000, you felt satisfied in your choice. One cannot always win such games.
However, as you are walking home one day you find yourself before the Predictor once more. He explains how he's had a cunning idea. This time round, he's either made a prediction and filled the boxes appropriately, or he hasn't gone to the effort and will wait till you announce your choice and then surreptitiously fill the boxes as necessary. The Predictor does these options with equal frequency.
As you contemplate this, you receive a tap on the shoulder. You turn round to find yourself faced with yet another Being, who introduces himself as the Meta-Predictor. He can not only predict your actions, but he also has a great track record of predicting the actions of the Predictor. The Meta-Predictor tells you this:
"You will either choose A and B, and the Predictor will fill the boxes after the fact, or you will opt to take only box B, and the Predictor has already made his decision and the boxes already contain the right amount of money."

Puzzled, you contemplate matters a little further...
So I've previously blogged on the Sleeping Beauty problem as well as on Newcomb's Paradox. The latter has caused some considerable discussion amongst myself and a couple of colleagues, and to my delight we don't all agree on it.

I'll probably post further on it as the discussion develops, but I stumbled across an interesting overlap between the two.

In order for Newcomb's Predictor to do the prediction, he must presumably either read some memory of previous discussion (so poor old Chaz, having been introduced to it and found himself a two-boxer is doomed to not win the £10 million!) or somehow simulate the event.

Being a fairly materialist person, I strongly suspect that a simulation of myself would be self-aware just as I am. In that case, on meeting the Predictor and being presented with two boxes, I have no idea if I am really me or a simulated me for the purposes of the Prediction.

In that case, I am rather likely Sleeping Beauty, about to have her memory wiped.

I may make a choice only to cease to be, with that choice acting causally forwards in time in order to allow the apparent violation of causality that would allow the Predictor to act as described in the problem.

In that case, although I may be a firm believer in causality and that future actions cannot affect the past, I may have good reason to believe that in this particular circumstance my actions may well effectively do that.

It's an interesting crossover, but really this little curiosity is either a sidetrack or a weakener of the core issues that make this such a puzzler.

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On the BHA's response

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Not so long ago, the Science and Technology delivered their report on homeopathy. It wasn't to homeopaths tastes. If you haven't heard of the story, I recommend Martin Robbins' piece for the Guardian.

The British Homeopathic Association has felt the need to respond. I thought I would take a look at parts of it.

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Edd works somewhere between astronomy and computing and has a general interest in science, skepticism and other related topics.

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