Use the procedures shown in Chapter 15 to explore the structure underlying the set of questions designed to assess the impact of sleep problems on various aspects of people’s lives. These items are...

Use the procedures shown in Chapter 15 to explore the structure underlying the set of questions designed to assess the impact of sleep problems on various aspects of people’s lives. These items are labelled
impact1
to
impact7. Run Parallel Analysis (using 121 as the number of cases and 7 as the number of items) to check how many factors should be retained.