There are only twelve types of people.

Esther links, in her usual odd way, to this calculate-your-Zodiac-sign thing. Now, while the idea that events in our lives are influenced by flaming balls of gas billions of miles away from us and from each other to such an extent that we can make accurate predictions by observing the patterns that those balls happen to form when viewed from Earth is not only patent nonsense but empirically inadequate, I've always been amenable, at least in theory, to the idea that the time of year at which we're born might have some bearing on our personality. I don't think for one minute that the stars would have anything to do with it, but other factors, such as climate and daylight, might. Or might not. In a world in which the temperature at which crocodile eggs are incubated decides the gender of the hatchlings, it's not that far-fetched that people born in June might be more irritable than those born in January.

So, in a spirit of scientific enquiry, I took the test. It was utterly wrong.

According to our analysis, you are a Virgo, Aug 23 to Sep 22.

Not even close.

But you are certainly not a Cancer, June 22 to July 22.

OK, that's true. But divining what star sign I'm not is unimpressive.

Based on my answers, the results give a score from 0 to 100 for each star sign, with 0 being a total mismatch and 100 being a perfect match. My lowest score — for Cancer — is 50, which just goes to show how full of Barnum's phrases the definitions are. It would be interesting to see how low a score anyone can get. My guess would be that people rarely score below 40 for any sign. My second-lowest score, 52, was for my real star sign, Aries. So that's pretty bloody wrong, then.

The test's bold assertion that I am definitely a Virgo is based on a mere 73. That's not very high, is it? The closest match I have to any of the definitions is three quarters. Even if the test had got me right, I wouldn't be impressed by a mere three-quarter match.

As it turns out, that's the whole point:

When a credulous person reads a description of their personality based on their sun sign, what do they do? In my experience, they go through and they pick up on some adjectives (such as 'blunt' and 'ambitious'), which they feel described them, and skip over the others. They notice all the adjectives they feel pertain to their personality, and, ignoring the misses, their faith in astrology is strengthened. It's a pernicious problem for all skeptics to address. But, if the tables are turned and your self-evaluation is used to place you into an astrological category, instead of being forced to fit the category given to you by birth, then your willingness to deceive yourself may be made evident. Most people read only their astrological description and accept it; they don't go through and read them all to see if one suits them better. In this way the real value of my reverse astrology test is found primarily in its one-time use by an individual; the statistical results are not nearly as useful.

Nice one.