after we reject the null hypothesis; it allow us to make multiple comparisons among
several means. So, it is appropriate to perform a post hoc comparison on these data.
B] Use the information provide in the ANOVA table to calculate R
2
. Interpret the effect size using
Cohen's conventions. State what this R
2
means in terms of independent and dependent variables
used in this study.
This R
2
of 0.50 is large. 50% of the total variation of dependent variables is
explained by variation of independent variables.

62) Orthodontics and one-way between-groups ANOVA: Iranian researchers studied factors affecting
patients' likelihood of wearing orthodontic appliances, nothing that orthodontics is perhaps the area of
health care with the highest need for patient cooperation (Behanam & Pooya, 2007). Among their
analyses, they compared students in primary school, junior high school, and high school. The data that
follow have almost exactly the same means as they found in their study, but with far smaller samples.
The score for each students is his or her daily hours of wearing the orthodontic appliances.
Primary school: 16, 13, 18
Junior high school: 8, 13, 14, 12
High school: 20, 15, 16, 18
A] What is the independent variable? What are its levels?
The independent variable is the type of school and its levels are: Primary school,
Junior high school, and High school.
B]
What is the dependent variable?
The dependent variable is the daily hours of wearing the orthodontic appliances
(score.)
C] Conduct all six steps of hypothesis testing for a one-way between-groups ANOVA.