1. p=0.05 means that one result in 20 is going to be the result of chance.
2. It's generally pretty easy (especially in psychology) to do 20 experiments, cherry-pick -- and publish! -- the p=0.05 result, and throw away the others.
The result is that published p=0.05 results are much more likely than 1 in 20 to be the result of chance.
1. p=0.05 means that one result in 20 is going to be the result of chance.
2. It's generally pretty easy (especially in psychology) to do 20 experiments, cherry-pick -- and publish! -- the p=0.05 result, and throw away the others.
The result is that published p=0.05 results are much more likely than 1 in 20 to be the result of chance.