p value

Introduction

A p value < 0.05 represents a < 5% chance a result is a result of chance alone.

A p value < 0.05 is most often used as the threshold of statistical significance.

Notes

In statistics, a value very close to the probability of making a Type I error, the error of rejecting a true null hypothesis.

A null hypothesis means no statistical significance, with any differences in populations or samples being due to chance.

To make a Type I error is to find statistical significance when it is not there, as in mistaking chance results for treatment effects.

For findings to be statistically significant, the probability of making a Type I error must be small, the smaller the better.

The traditional cutoff value is 5%.

If a p value is 5% or less (p < 0.05), the null hypothesis can be rejected & there is statistical significance.

Proposal to lower p-value threshold for significance to 0.005