Date: 01/2008
Journal: Seminar of Hematology
Summary :
- Twelve P- Value Misconceptions: If P=.05, the null hypothesis has only a 5% chance of being true.
- A non significant difference (eg , p.>or =.05) means there is no different between groups.
- A statically significant finding is clinically important.
- Studies with p values on opposite sides of .05 are conflicting .
- Studies with the same p values provide the same evidence against the null hypothesis.
- P=.05 means that we have observed data that would occur only 5% of the time under the null hypothesis.
- P=.05 and p<or =.05 mean the same thing.
- P values are properly written as inequalities (e g, “p<or = ,02”when p=,015)
- P=.05 means that if you reject the null hypothesis, the probability of a type I error is only 5%.
- With a p =,05 threshold for significance, the chance of a type I error will be 5%.
- You should use a one- sided p value when you do not care about a result in one direction, or a difference in that direction is impossible.
- A scientific conclusion or treatment policy should be based on whether or not p value is significant.
