Table 1.

Illustration of the 2 types of statistical errors.

		Truth
		No Difference^{^a} Between Groups or Association Between Variables	Difference^{^a} Between Groups or Association Between Variables
Results of the research study	No statistically significant difference between groups or association between variables	True negative finding	False negative finding (ie, type II error)^{^b}
	Statistically significant difference between groups or association between variables	False positive finding (ie, type I error)	True positive finding

↵^aThe difference is a prespecified value that is the alternative hypothesis of the statistical test.
↵^bNote that statistical power is equal to 1 minus the probability of a type II error.