Misconception #1: If P.05, the null hypothesis has only a 5% chance of being true.
Misconception #2: A nonsignificant difference (eg, P .05) means there is no difference between groups.
Misconception #3: A statistically significant finding is clinically important.
Misconception #4: Studies with P values on opposite sides of .05 are conflicting.
Misconception #5: Studies with the same P value provide the same evidence against the null hypothesis.
Misconception #6: P .05 means that we have observed data that would occur only 5% of the time under the null hypothesis.
Misconception #7: P .05 and P <.05 mean the same thing.
Misconception #8: P values are properly written as inequalities (eg, “P <.02” when P .015)
Misconception #9: P .05 means that if you reject the null hypothesis, the probability of a type I error is only 5%.
Misconception #10: With a P .05 threshold for significance, the chance of a type I error will be 5%.
Misconception #11: You should use a one-sided P value when you don’t care about a result in one direction, or a difference in that direction is impossible.
Misconception #12: A scientific conclusion or treatment policy should be based on whether or not the P value is significant.