Evaluate the following research designs. Pay close attention to the methods used and the efforts taken to control relevant variables. What do you see as threats to the either the internal or external validity of the research?
A researcher wanted to find out if a new method of training assembly workers to recognize defective integrated circuits was superior to the standard training method. The researcher designated one assembly plant in southern California as the experimental group, and an assembly plant in southern Texas as the control group. Both plants had about the same number of workers, the same production load, and comparable pay and benefits for workers. The workers had almost all been there a number of years and were familiar with past training procedures. At the experimental plant, workers received the new one-day training program on recognizing defective integrated circuits, while the control group received the standard one day training. Personnel from the Performance Improvement Department at each plant conducted the training. The rate of recognizing defective parts before being assembled was significantly better at the plant that received the new training method.
A manager at a car dealership was concerned that her sales people too often had to look up answers to customer questions regarding car specifications. She wanted her sales people to appear more knowledgeable about the cars they were selling. She decided to experiment with some new training methods and materials. She randomly assigned her sales people to either the day or night shift. For the day shift she used the new training methods and materials, the night shift received the traditional approach. Her new approach involved a pretest to find out what her sales force already new before beginning the training. The day shift received this test a week before the training took place. This information would help her fine tune the new training approach. The night shift received their training the first week, while the day shift received their training the one week later. After both groups had received their training, she told her sales force that she would count how often they had to reference specification books by making them check the books out through the receptionist. At the end of one month she found that both the treatment group and the control group rarely needed to reference the specification books anymore.