Does the job satisfaction of assembly workers differ when their work is machine$$paced rather than self$$paced$?$ Workers are assigned either to an assembly line moving at a fixed pace or to a self$$paced setting. All subjects work in both settings, in random order. This is a matched pairs design. After two weeks in each work setting, the workers take a test of job satisfaction. The response variable is the difference in satisfaction scores, self$$paced minus machine$$paced$.$

The parameter of interest is the mean $$ of the differences in scores in the population of all assembly workers.