Against Astrology -Part II - Experiments

*Warning* A VERY long post below. But important. Please read. And patiently... bad language in commented is NOT appreciated. And only two limericks ... am in a hurry, with exams coming up and all. :-)

Today's Bombay Times is fat (sigh)
They have a special on "Gemini"
Their 12th anniversary
But they're still in nursery
They can't separate fact from crap, that's why!

In the previous post, we dealt with the theoritical refutation of astrology. It's good enough on it's own (for all theory is of course experimentally confirmed), but here, I plan to deal with more serious and convincing issues: Hidden Persuaders, Tests of astrology, and whether astrology has any importance today. A very useful reference is Skepdic's article on astrology, and the links below it. Others will be cited below.

Hidden Persuaders

Why do scientists reject astrology even though we can see that it works? I mean, anyone would agree with their descriptions they read in their horoscopes, sun-sign charts, etc. So, why do these "skeptics" refuse to believe?

That's because they know of the existence of "Hidden Persuaders". An example is the Forer effect: Psychologist Bertram Forer made his students take a personality test, and gave each of them a result, and asked them to rate the evaluation's accuracy. The average was 85%... everyone thought the description was accurate for themselves. But, he had given each student the same evaluation! This is what's called a hidden persuader : we ignore the inaccurate aspects and concentrate only on the ones which apply to us.

A list of hidden persuaders:
Confirmation Bias, Self Deception, Subjective Validation, Barnum Effect, Communal Reinforcement , Testimonials etc. Do read the linked articles, they're readable and informative.

In short, hidden persuaders are things which lead us to wrong conclusions because we are biased. When we read a horscope, or a personality description, we are biased, and think it is accurate and describes us. This isn't harmful in itself, but when we are led into spending money and time upon it, it becomes so.

Tests of Astrology

My principal reference for this section is a paper by Dean and Kelly : "Is astrology relevant to consciousness and psi?" (a pdf link). The paper contains much more information than just the tests, including some information on astrologers' views, hidden persuaders, etc.

The most trusted tests conducted are known as "Control group double-blind tests". In these tests, control groups are used, and neither experimenter nor subjects know who the controls are. This is essentially to remove the effects of the hidden persuaders.

Now we come to the tests of astrology. Tests which study the rlation between astrology and consciousness, psi are important because without scientific explanation, astrologers resort to psychic explanations, or to unknown forces. These can only be measured by experiment. A note about effect sizes: an effect of 0.4 means 70% accuracy where 50% would be that expected by chance. This is how the accuracy of the tests is measured. If astrology is right, effect sizes should be atleast 0.5.

Astrology asserts that one's life depends on the positions of stars at one's birth... in effect, on thebirth time. Time twins are a perfect test of astrology. "Time twins" refers to people who are born very close to each other in time. A study (unconnected with astrology) consisted of 2101 persons born in London from 3-9 March 1958, born on average 4.8 minutes apart. 110 relevant variables like IQ, rating for behaviour, etc, were measured at ages 11, 16 and 23, with16 variables as controls. Many of the 110 are supposed to be included in the birth chart. But the effect sizes due to astrology are calculated to be 0.00+- 0.03 . Time twins do not show any similarities which astrology says must be there.

Astrologers are however convinced that the birth chart is so complex that a single factor cannot be tested. If birth charts are so complex, how do astrologers themselves read them? Tests of astrologer accuracy have been conducted, and a meta-analysis of these gives a mean effect size of 0.051. Tests of astrologer agreement (meta-analysis) give an effect size of 0.101. Astrologers are not accurate in matching birth charts to profiles, and they don't even agree with each other.

We can, thus, say that even when tested, astrology does not work.

Why no Astrology?

I'd give a simple enough reason: It doesn't work.

But, astrology is still practised and believed in many parts of the world. It is harmful, because millions of dollars are spent on something that doesn't work. Some people seem to think that clients get comfort from the advice given, and thus astrology serves it's purpose. That is, simply and plainly, wrong. Two reasons:

Critical Thinking. The Bad Astronomer mentions this on his blog, and it is as important a reason as anything: Critical thinking is essential to humanity's survival. Scientific, organised thinking is what has caused humanity to come so far. Unless we recognise our biases and seek the truth in a controlled way, we'll not progress. Astrology destroys this essential skill.

Secondly, astrologers do not advice people, they just suggest them to change their names, hold rituals, or something like that. That will not help, except misleading people into thinking they're on the right path. It'll lead to harm. Astrology can be used in counselling: www.astrology-and-science.com has two articles advising astrologers in counselling, but they mostly ask them to use astrology only as a device to connect with the subject, and concentrate on counselling, not astrology.

So, here is The Grand Conclusion:

The conclusion grande, in a song
Holding my tongue in a tong
(I don't want to pout)
But can't stop the shout:
Astrology is (really, really) wrong!!!!

Having supported the statement with theoritical as well as experimental evidence, I hope you'll keep away from astrology. And spread the message.

Thanks. Do comment.