User experience professionals salary survey. The User Experience Professionals Association (UXPA) supports people who research, design, and evaluate the user experience of products and services. The UXPA periodically conducts a salary survey of its members (e.g., UXPA Salary Survey, November 2014). One of the authors of the report, Jeff Sauro, investigated how much having a Ph.D. affects salaries in this profession and discussed his analysis on the blog, www.measuringusability.com. Sauro fit a first-order multiple regression model for salary (y, in dollars) as a function of years of experience (x1), PhD status (x2 = 1 if PhD, 0 if not), and manager status (x3 = 1 if manager, 0 if not). The following prediction equation was obtained:
a. Predict the salary of a UXPA member with 10 years of experience, who does not have a PhD, but is a manager.
b. Predict the salary of a UXPA member with 10 years of experience, who does have a PhD, but is not a manager.
c. Why is a 95% prediction interval preferred over the predicted values given in parts a and b?