Final answer:
The value of r in the Student-Newman-Keuls comparison depends on the number of adjacent means included, which is related to the number of groups being compared.
Step-by-step explanation:
In a Student-Newman-Keuls comparison, the value of r for the q statistic will vary depending on the number of adjacent means included in the comparison. The value of r depends on the number of adjacent means included in the comparison (option c). The Student-Newman-Keuls test is a post hoc test used after an ANOVA to make multiple pairwise comparisons between group means to find out where the differences lie.
The q statistic used in this test compares the differences between group means. The critical value of q is obtained from a table and varies with the number of groups or treatments being compared, the total number of observations in the analysis, and the desired significance level. It's important to note that the sample size and standard deviation are factors in calculating the overall test statistic in ANOVA, but r for the q statistic specifically depends on the number of comparisons being made.