We Are Trying to Evaluate the Efficacy of a Treatment

Multiple Choice

We are trying to evaluate the efficacy of a treatment for claustrophobia. We have a control group that receives no treatment and an experimental group that receives our new treatment. We ask each participant to enter a very small room and stay there are long as they can. The mean of the control group is 10 seconds, with a standard deviation of 4 seconds. The mean of the experimental group is 18 seconds with a standard deviation of 8 seconds. Our best estimate of effect size is

A) 2.0
B) 1.33
C) 1.0
D) 1.75