Linear combinations of means, and in particular contrasts, play an important role in analysis of variance (ANOVA). Through understanding and analyzing contrasts, meaningful inferences about the population means can be made. Even the classic ANOVA hypothesis can be expressed as a set of contrasts. In this lesson, we will define linear combination, contrast, and then investigate the distributional properties of a single contrast. We will broaden our consideration to simultaneous inferences on multiple contrasts.