Experimenting on Astrology, one sign at a time

Today was session number two for 2012 and I decided to have a crack at astrology. As popular as it is this is the first time we’ve really looked at it. We’ve discussed it plenty of times but haven’t really examined how it works. Over the next few sessions I plan on talking to the kids about the different kinds of astrology and the theories behind why it’s supposed to work. I like them to know as much as possible about various pseudo-sciences to enable them to better discuss it with others.

For today’s experiment I trawled the web looking for star sign personality descriptors. I took each of them and replaced the real star sign name with a fake one. For example, Cancer is now the Lobster and Leo is now the Spare Tire. Students were instructed to read each description and determine which one they felt represented them the most. My theory was that if the star signs were accurate, most of the students would select the correct option.

Star signs activity

Star signs activity – answers

This experiment does rely on the laws of probability behaving themselves. It would be wasted on a handful of people but I was hoping to get at least 30 students turning up. A lot of students were rehearsing for the house musical festival so numbers were unfortunately down, but I did manage to wrangle up 27 participants.

Assuming that these personality descriptors were nothing more than Barnum statements, we would assume that roughly 1 out of 12 participants would select the correct star sign. In my example that would mean around 2 – 3 correct guesses, or 8 – 11% correct. Knowing full well that my students are deceitful little monsters I made sure that they wrote down their real star sign before I revealed which was which.

The students read through their sheets and tried to choose the description which they felt best matched their personality. Most of them struggled to do so because they couldn’t choose just one. On average around 4 options seemed suitable to each student. If we stick to our assumption regarding the Barnum statement then that shouldn’t have been a surprise.

After a few minutes of reading and explaining the longer words to the year sevens (mental note: make sure they’re easily understandable to twelve year olds) I collected their data. This is where I made my first mistake. Despite being married to a psychology teacher, it never occurred to me to get advice on how to record the student’s answers. This led to a bit of awkwardness while I tried to decide how to count the number of guesses for each fake star sign plus the numbers of each real star sign and so on. I wound up just reading out the answers and counting how many kids got it right.

Fortunately, the gods of probability were smiling on me and only 3 students selected their own star sign which works out to just over 11%. Of course the number of participants were too small to consider this statistically significant but it was still a good way of showing the kids how research into pseudoscience can be carried out. I made sure to explain to them that we had not just disproved astrology. All we had done was provide a tiny bit of extra evidence that astrology is probably bunk.

The kids enjoyed it but none of them were blown away with the results. In fact, when I announced that we would be studying astrology one yelled out “It’s crap!” before we even began. Astrology is a wonderful topic to study but I believe that it is a lesser-believed one. Psychics and quacks have better marketing and it is harder to convince people what they are really doing. Years of reading dodgy horoscopes in the newspaper have whittled away a lot of the public’s belief in the power of the stars.

For our next session I’ll be introducing the kids to the history of astrology and some of the “science” behind it. Remember, knowledge is power and power lets you go around being annoying to all of your friends.



Filed under McKinnon Secondary Sceptical Society

2 responses to “Experimenting on Astrology, one sign at a time

  1. I have tried a similar thing and struggled with the fact that each student will find a number of signs that they relate to. Consequently, when I say Number 1 was Scorpio, the believers who consider themselves to be a scorpio, but chose another sign, will immediately look at the ‘correct’ scorpio reading, say they were thinking of that one too, and changed their mind at the last minute. I their minds it then becomes a hit. Thus 4 out of 12 could end up being considered a hit by the student – a 1 in 3 chance! Depressing, isn’t it?


    • Adam vanLangenberg

      Exactly, that’s why I made them write everything down first. I also made sure their friends could see what they’d written and accuse them if they cheated 🙂

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