LAUSR

As a novice researcher, the clinical nurse specialist may not be familiar with some of the less used statistical tests that are available to them.One test that can be especially useful is the 1-way analysis of variance (ANOVA) test. This test is useful when 3 or more groups are considered in a study. The intent is to determine if 2 (or more) groups differ on some outcome variable that is measured at a ratio or interval level. A special version of the ANOVA called analysis of covariance (ANCOVA) can also be useful when it is important to statistically control for some extraneous variable that might otherwise impact the outcome variable and obscure the results of your intended comparisons (Figure 1). The purpose of this article is to discuss the ANOVA and ANCOVA statistical tests and to explain the assumptions of the test and methods used to test the assumptions. Finally, the importance of power and sample size related to these 2 tests will also be explained.