In regard to age, Kymissis (1993) recommends that certain adolescent ages not be mixed. For example, high school freshmen and sophomores do not mix well with juniors and seniors. However, he reports that there is little difficulty in mixing college undergraduates, although undergraduates and graduate students are not easily combined. Age in the adolescent years may not be quite as sensitive a variable as during childhood. Nevertheless, it appears that older adolescents are less affected by age differences than are younger adolescents