In this dissertation, Eberhard analyzed the impact of a daily, in-school chess intervention on student cognitive performance on the Cognitive Abilities Test (CogAT) and the Naglieri Nonverbal Ability Test (NNAT). Conducted in a rural middle school in southern Texas during the 2001-02 school year, the study’s sample was comprised of 60 treatment group students and 77 control group students in grades 7 and 8. Students were allowed to choose to enroll in one of several elective courses, including chess and keyboarding. Data were analyzed using paired t-tests and two-way ANOVA. The author found an effect size of -0.085 standard deviation units. However, the results were statistically insignificant suggesting no difference between treatment and control students. The study was eligible for inclusion in the systematic literature review and categorized as a Tier III study. Because the study does not control for differences in groups on pretest results, the null effect may be due to differences in the students who participated in the treatment and control groups, as opposed to a null effect for the intervention. Self-selection into the intervention instead of the keyboarding course may be indicative of some systematic unobserved difference between the groups, thus producing potentially biased results.