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
ELI5:
Let’s assume you believe that a medicine helps against a disease.
So you do an experiment and give 10 sick patients your medicine.
Usually 50% of the patients die. With the medicine in your experiment, only 40% die. So does your medicine actually help?
50% death rate is only an average over a large group and 10 people is a small group. By pure luck, sometimes only 40% die even without any medicine. The p value is the probability that a result happens by pure luck without the effect you want to test.
So a large p-value means: this result happens often, even without any medicine. Your result is not very significant, it doesn’t say a lot about your medicine because it happens all the time.
A small p-value means: this result happens very rarely without medicine. The result is significant and at least a hint that the medicine might actually help, because if it doesn’t this is an unlikely result.
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