Question

1. a teacher wants to know if a new tutoring program improves math scores. she lets students choose whether they join the program or not. what is the biggest flaw in this design?

○ too small a sample size
○ randomization is missing
○ no control group
○ to guarantee the results match the hypothesis

Explanation:

The teacher’s design lacks randomization (students choose participation), which introduces selection bias. Without random assignment, differences in math scores could stem from pre-existing traits of students who chose to join, not the tutoring program itself. This violates experimental validity for causal inference.

Answer:

B. Randomization is missing