Many utility companies have introduced programs to encourage energy conservation among their customers. An electric company considers placing small digital displays in households to show current electricity use and what the cost would be if this use continued for a month. Will the displays reduce electricity use? One cheaper approach is to give customers a chart and information about monitoring their electricity use from their outside meter. Would this method work almost as well? The company decides to conduct an experiment to compare these two approaches (display, chart) with a group of customers who receive information about energy consumption but no help in monitoring electricity use. 60 single-family residences volunteer to take part in this study and each residence is randomly assigned to one of the treatments. Why was it important to include a control group that received only information about energy consumption, but no help in monitoring electricity use?
