A researcher examines the relationship between the quality of breakfast and academic performance for a group of elementary-school children. For each child, the researcher interviews the parents to...

A researcher examines the relationship between the quality of breakfast and academic performance for a group of elementary-school children. For each child, the researcher interviews the parents to obtain information about the child’s typical breakfast, and uses school records to obtain a measure of academic performance.

 Explain why this study is not a true experiment.