I have actually been studying and using statistics a lot in my career, but I still struggle with finding a simply way to explain what exactly is p-value.
In: Mathematics
You can see a pattern due to random luck and you could misinterpret it to suggest some underlying factor that isn’t really there. P-value measures how likely (or unlikely) it would be for this particular result to appear just by random chance. The smaller it is, the more likely that the result is meaningful and not just lucky.
Imagine you give a drug to 2 people who are moderately sick, and they both get better. It’s totally possible they both got lucky and would have gotten better anyways without the drug. It’s going to be really hard to tell with only 2 people, so if you analyze the P value you would find it’s likely high, indicating there is a large chance you just got lucky and you can’t take any meaningful lessons from that study.
However if you don’t give 1000 people a drug, and find only 20% get better on their own, then you do give 1000 people a drug and 80% get better, that’s a very strong pattern outside the “random luck” behavior you were able to observe. So if you analyzed that P value it would likely be small, indicating it was more likely that the drug really did cause this result, and it wasn’t just luck.
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