Question: A researcher investigates whether single people who own pets are generally happier than singles without pets. A mood inventory questionnaire is administered to a group of 20- to 29-year-old non-pet owners and a similar group of pet owners. The pet owners are matched one-to-one with the non-pet owners for income, number of close relationships, and general health. The data are as follows:

Is there a significant difference in the mood scores for non-pet owners versus pet owners? Test with α = .05 for two tails.