Chapter 4.2, Problem 58E

To determine

To explain what flaw in the design of this experiment makes it impossible to say if the bonus really caused the increase.

Explanation of Solution

In this study, researchers examined that if the unemployed people were given the cash bonuses if they find a job within $15$ weeks then the speed to return to work of the unemployed people increases or not.

Thus, the group of unemployed people were observed by increasing the cash bonus given if they find a job and the result increases. But, in this experiment there is a flaw in the design because there are other factors that can influence the increase in the speed to return to job of the unemployed people. For the accurate result the control group should be there to compare the result and a placebo should be used so that correct rate should be identified by the researchers.