9/21/2023 0 Comments Data dredgingUnfortunately, while the p-values reported by the scientists are (presumably) mathematically correct, the wording in the newspaper is misleading and would only apply if green jelly beans were the only ones tested. This finding leads to a big newspaper headline saying Green Jelly Beans Linked To Acne where it is said that they have 95 percent confidence with only a 5% chance of a coincidence. They test 20 different colors, each at a significance level of 5%. p > 0.05), but then Megan and Cueball ask them to see if only one color of jelly beans is responsible. The scientists find no link between jelly beans and acne (the probability that the result is by chance is more than 5% i.e. Minecraft was previously referenced in 861: Wisdom Teeth. The important point is this – there could still be a 1 in 20 chance that this result was purely a statistical fluke.Īt first, the scientists do not want to stop playing the addictive game Minecraft, but they do eventually start. If, however, the chance that their result was purely by random chance is greater than 5%, they will say they have found no evidence of a link. If they find that more of the people who ate jelly beans had acne and the chance it was a purely random result is less than 1 in 20, they will say that jelly beans do cause acne. In the comic the scientists choose a threshold of 5%. Before we start the experiment, we choose a threshold known as the significance level. This is known as statistical hypothesis testing. However, to give more confidence in the result of this type of experiment, scientists use statistics to see how likely it is that the result they find is purely by chance. Of course, it is very unlikely that all the acne prone people end up in one group by chance, especially if we have enough people in each group. What if, purely by chance, all the group we selected to eat jelly beans would have had acne anyway while those who didn't eat jelly beans were the lucky sort of people who never get spots? Then, even if jelly beans did not cause acne, we would conclude that jelly beans did cause acne. There is an element of chance in how many people prone to acne are in each group. Some people will suffer from acne whether they eat jelly beans or not, and some will never have acne even if they do eat jelly beans. If more people in the group that eat jelly beans have acne, then you might think that jelly beans cause acne. After some time you compare whether the group that eat jelly beans have more acne than those who do not. To do this you could find a group of people and randomly split them into two groups - one group who you get to eat lots of jelly beans and a second group who are banned from eating jelly beans. Let's imagine you are trying to find out if jelly beans cause acne. They find no link, but in the end the real result of this research is bad news reporting!įirst, some basic statistical theory. A girl with a black ponytail comes to Cueball with her claim that jelly beans cause acne, and Cueball then commissions two scientists (a man with goggles and Megan) to do some research on the link between jelly beans and acne. This comic is about data dredging (aka p-hacking), and the misrepresentation of science and statistics in the media. It was probably a- "RESEARCH CONFLICTED ON GREEN JELLY BEAN/ACNE LINK MORE STUDY RECOMMENDED!" Title text: So, uh, we did the green study again and got no link.
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