A research specialist for a large seafood company investigated bacterial growth on oysters and mussels subjected to three different storage temperatures. Nine cold storage units were available. Three storage units were randomly assigned to be used for each of the storage temperatures: 0, 5, and 10° C. Oysters and mussels were stored for 2 weeks in each of the cold storage units. A bacterial count was made from a sample of oysters and a sample of mussels from each storage unit at the end of 2 weeks, so that for each storage unit there is a bacterial value for oysters and a bacterial value for mussels, yielding a total of 18 observations.