(From my thesis: Enhancing Proficiency in Communication through Campus Journalism)
Statistical Treatment of Data
In order to get the true measures of the answers needed on the statement of the problem the inferential statistics will be used (Trochim 2006). With inferential statistics, the study will try to reach conclusions that extend beyond the immediate data alone. The inferential statistics will be used to make judgments of the probability that an observed difference between groups is a dependable one or one that might have happened by chance in this study. Thus, inferential statistics is used to make inferences from the data to more general conditions; descriptive statistics is used simply to describe what's going on in the data. In addition, whenever there is a need to compare the average performance between two groups the t-test for differences between groups was used
The t-test assesses whether the means of two groups are statistically different from each other. This analysis is appropriate to compare the means of two groups.
Figure 1. Idealized distributions for treated and comparison group posttest values.
Figure 1 shows the distributions for the treated (blue) and control (green) groups in a study. The figure shows the idealized distribution -- the actual distribution would usually be depicted with a histogram or bar graph. The figure indicates where the control and treatment group means are located. The question the t-test addresses is whether the means are statistically different.