This week we looked at probability, judgement and frequency and how generally people have a misconceived idea about probability and ideas towards it. First we look at the birthday probability where we were asked how many people it would take to find 2 people with the same birthday.
My first thought was 366. However the answer was just 23. This is a prime example of where people have a very misconceived idea about probability. Another example is that of the lottery. I personally have never played. I have never seen the point as I am unlikely to win, however you have to be in it to win it. The probability of winning the lottery is about 49 million to 1, yet people still always play, and with the same numbers each go. They systemize their numbers with makes the likelihood to them winning even less. The probability of the lottery is very inaccurate and most people would be better off with a lucky dip. In the case of the lottery however I think it is more that case that people try to make sense out of randomness. And this is why they often systemize their numbers
It is not however the probability of the lottery that is inaccurate, it can be newspapers as well. There was a story that suggested that there was an increased risk of cancer for people taking the pill. People then stopped taking the pill, which also had risks. This also proves that people’s intuition of probability is very poor and often inaccurate, and that there is a perceptual bias in probability judgement.
This was also proven in class when we had to do a coin toss probability test. We were asked how many times there would be a change in lead between heads and tails out of 101 tosses. I thought the answer was 25. The answer was 0. It has proven that my personal intuition for probability it quite poor. In class we were also introduced to the idea of heuristics that are shortcut ways of thinking, and found that people are more sensitive to sample size and when it comes to probability are affected by the recency, familiarity and vividness. This is what most people do when answering a probability answer; they try to make sense out the randomness. Just the like the example of weather patterns and randomness.
Overall though due to this lesson I have found that the answer that seems likely is generally not the right answer, and to always think twice before answering a probability question.
Regarding your comment about sample size, what has been suggested is that people are insufficiently sensitive to sample size (as in the case of Kahneman and Tversky's hospital problem.
ReplyDeleteIn the question about coin tosses, 0 is the single most likely outcome. Nonetheless, it's still more likely that there will be SOME lead changes, but in terms of the single most likely outcome the answer is zero.
One thing I didn't mention, but which you may have observed in your own coin tosses, is that the overall distribution of heads and tails is usually still close to 50-50, even though the lead may not have changed much or at all.