What do tests of differences primarily help to determine?

Tests of differences are statistical methods used primarily to determine if there are significant differences between groups concerning certain variables. The focus of these tests is usually to compare mean scores across different groups. For example, a t-test or ANOVA would analyze whether the average scores of two or more groups are significantly different from one another, which is essential in assessing the impact of various interventions or conditions.

This approach is particularly useful in research where the primary interest lies in understanding if characteristics or outcomes vary between groups, such as treatment and control groups in clinical trials. By identifying whether the mean scores differ, researchers can draw conclusions about the effectiveness of different treatments or the influence of certain factors.

The other options relate to different aspects of statistical analysis. They involve investigating relationships between variables, examining how data points are distributed, and planning for the appropriate sample size to achieve statistically significant results. However, these are not the primary focus of tests of differences, which are specifically concerned with comparisons of means among groups.