ABSTRACT
Parametric statistical procedures allow students to draw inferences about populations based on samples of those populations. To make these inferences, their must be able to make certain assumptions about the shape of the distributions of the population samples. In hypothesis testing, we create two hypotheses that are mutually exclusive and all inclusive. They refer to those two hypotheses as the null hypothesis and the alternative hypothesis. The null hypothesis generally states that any difference we observe is caused by random error. Most statistics textbooks present hypothesis testing by using the concept of a critical value. PASW output generally includes a two-tailed alpha level. A two-tailed hypothesis attempts to determine whether any difference exists. Analysis of variance is a procedure that determines the proportion of variability attributed to each of several components. It is one of the most useful and adaptable statistical techniques available.
