Weller and Weller (1997) conducted a study of the tendency

Weller and Weller (1997) conducted a study of the tendency for the menstrual cycles of women who live together (such as sisters) to become synchronized. For their statistical analysis, they compared scores on a measure of synchronization of pairs of sisters living together versus the degree of synchronization that would be expected by chance (lower scores mean more synchronization). Their key results (reported in a table not reproduced here) were synchrony scores of 6.32 for the 30 roommate sister pairs in their sample compared to an expected synchrony score of 7.76; they then reported a t score of 2.27 and a
p level of .011 for this difference. Explain this result to a person who is familiar with hypothesis testing with a known population variance, but not with the t test for a single sample.