A Researcher Wishes to Study the Relationship Between the Level

Multiple Choice

A researcher wishes to study the relationship between the level of background noise and mental concentration. The treatment (noise level) will have three levels: no noise, low-intensity noise, and high-intensity noise. the subjects are to be divided into three groups, and each group is to receive one of the treatments. He has available to him a set of 60 female volunteers and a set of 90 male volunteers. What experimental design strategy would help him eliminate the introduction of gender as a confounding variable? ​

A) stratified sampling
B) replication
C) blocking
D) systematic sampling
E) double-blind trials