In the population of children in a school district, the mean number of days tardy per year is 2.8. A sociologist obtained a sample of children from single-parent families and found the mean number of days tardy was 3.2. He used a single-sample z test to analyze the data, finding z (N = 28) = 1.68, p > .05. Interpret the results to see if coming from a single parent family is related to tardiness.