to evaluate training programs, researchers have tried to use several strategies. (a) one strategy is to compare the outcomes of those who entered the training programs (treatment group) with those who did not receive training (control group). list one group they considered. (b) what are the problems with using the control group you listed in (a)? list the problem, and explain how this problem will affect your estimate of the effect of the training program. note: you need to say whether the problem will lead to an over-estimation or an under-estimation of the treatment effect, and why. (c) another strategy is to compare outcomes of workers before and after they entered training programs. what is the problem with this strategy? list the problem, and explain how this problem will affect your estimate of the effect of the training program. note: again, you need to stay whether the problem will lead to an over-estimation or an under- estimation of the treatment effect and why.