What is the primary purpose of a t-test?

The primary purpose of a t-test is indeed to compare the means of two groups. This statistical test is specifically designed to determine whether there is a significant difference between the average values of two sets of data. For instance, if researchers want to find out if there is a difference in test scores between two different teaching methods, a t-test can analyze the means of the two groups (students taught by method A versus method B) to see if the observed difference is statistically significant or could be attributed to random chance.

In contrast, other choices focus on different statistical relationships. Correlation, as mentioned in another option, pertains to assessing how closely two variables are related, not specifically comparing their means. Analyzing the variance among multiple groups refers to ANOVA, which examines the differences between means from three or more groups rather than just two. Finally, assessing the strength of a relationship between variables relates to techniques used in correlation or regression analysis, which again do not involve direct comparisons of group means as a t-test does.