EXAMPLE 12.24

Comparing each pair of groups. Let’s return once more to the Facebook friends data with five groups (page 648). We can make 10 comparisons between pairs of means. We can write a t statistic for each of these pairs. For example, the statistic

= −3.59

compares profiles with 102 and 302 friends. The subscripts on t specify which groups are compared.

The t statistics for two other pairs are

= 1.11

= 2.90