Grace Conducts Research on Race and Achievement in Mathematics

Multiple Choice

Grace conducts research on race and achievement in mathematics. She designs a study to see if a new intervention she designed increases African-American students' math achievement scores. She goes to a local school with a representative Aftrican-American student population and randomly assigns college-bound African-American students to the intervention or to a control condition. Grace gives a mathematics achievement test in September to both groups. Through the academic year the treatment condition receives the intervention. She uses end of year achievement tests to see if there are differences between conditions.
-Which of the following external validity threats should most concern Grace regarding her study?

A) Selection
B) History
C) Instrumentation
D) Maturation