4 ms·
I'm having a hard time understanding why p-values are so hard to explain without resorting to jargon... it seems very intuitive to me, and none of these example
by ewzimm 11y ago
I'm having a hard time understanding why p-values are so hard to explain without resorting to jargon... it seems very intuitive to me, and none of these examples really put it in context.
I'd explain it like this:
It's easy to lie with statistics if you take them out of context. Maybe I have an idea that drinking flouridated water causes cancer, so I take a survey and find that 40% of people who drink flouridated water develop cancer. That number is meaningless without knowing how likely it is for people who don't drink it to develop cancer, which is about 40%, so the numbers match up 1:1, completely normal. In this case, 1 is the p-value, and it gives you a starting point for developing an experiment.
- nonbel 11y ago>"That number is meaningless without knowing how likely it is for people who don't drink it to develop cancer, which is about 40%. That's the p-value, and it gives you a starting point for developing an experiment." That is the frequency of cancer given not drinking fluoridated water. That is not a p-value.
- ewzimm 11y agoSorry, I saw how that could be misleading by saying that's so I clarified right away... not fast enough I see. I mean that comparing the observed data to a baseline gives you a p-value.
- nonbel 11y agoThis example is still misleading because you have selected a special case where the frequencies are exactly equal. In any other case the p value will depend on the sample size.
- ewzimm 11y agoTrue, but what I'm trying to convey is that if someone just wants to generally understand what a p-value is from no knowledge, understanding how to read a specific number isn't important. At first, I wasn't even going to include a specific number, but I realized not having one would be confusing in its own way. Looking at a specific p-value and understanding its significance is only useful once they're actually looking at a study. But first they just want to know how it's derived and what it's good for.