Construct two normal probability plots for the height data in Exercises 6-22 and 6-29. Plot the data for female and male students on the same axes. Does height seem to be normally distributed for either group of students? If both populations have the same variance, the two normal probability plots should have identical slopes. What conclusions would you draw about the heights of the two groups of students from visual examination of the normal probability plots?

Statistics for Psychology Concept 2 * z-test * single sample t test * used to compare a sample mean to a population with known mean, but the variance of the population is unknown * dependent means t test * also known as a “repeated measures” or “within subjects” research design because it compares two scores for each individual in the sample * Looks for a before and after effect * frequently seen in determining efficacy of a particular therapy or medication on a group of individuals * “before” scores as a baseline prior to a treatment * “after” scores gathered following a treatment or intervention (a dependent variable manipulation) * after minus before * unknown population mean and variance * two scores for each