For the 2014 study, "A Randomized Trial Examining the Effects of Aerobic Physical Activity on Attention-Deficit/Hyperactivity Disorder Symptoms in Young Children", researchers examined the effect of a daily before-school physical activity program on behavioral outcomes of students in grades K-2. The study sample included 202 students who either were identified as at risk for ADHD or showed typical development. The study authors randomly assigned students to receive either the physical activity intervention or a sedentary classroom-based program. The study authors then altered the random assignment of students in order to have more similar research groups and analyzed the student data based on the altered research conditions. The analysis included imputed outcomes for students with missing data. Because randomization was compromised, the study could not meet WWC group design standards without reservations. In addition, to meet WWC group design standards with reservations, the WWC requires that baseline equivalence of the analytic samples be demonstrated without imputed outcomes. The study did not demonstrate this baseline equivalence, so the study does not meet WWC group design standards. A glossary of terms is included. [The following study is the focus of this Single Study Review: Hoza, B., Smith, A. L., Shoulberg, E. K., Linnea, K. S., Dorsch, T. E., Blazo, J. A., Alerding, C. M., & McCabe, G. P. (2014). "A randomized trial examining the effects of aerobic physical activity on attention-deficit/hyperactivity disorder symptoms in young children". Journal of Abnormal Child Psychology. doi:10.1007/s10802-014-9929-y]