An open label study (where participants are aware of the treatment they are taking) is conducted to assess the time to pain relief following treatment in patients with arthritis. The following linear regression equations are estimated relating time to pain relief measured in minutes (dependent variable) to participant's age (in years), gender (coded 1 for males and 0 for females) and severity of disease (a score ranging from 0 to 100 with higher scores indicative of more severe arthritis):
Time to Pain Relief = -24.2 + 0.9 Age
Time to Pain Relief = 11.8 + 19.3 Male Gender
Time to Pain Relief = 3.2 + 0.4 Severity
Time to Pain Relief = -19.8 + 0.50 Age + 10.9 Male Gender + 0.2 Severity
A. What is the expected time to pain relief for a male following treatment?
Time to Pain Relief = ________
B. What is the expected time to pain relief for a participant aged 50 following treatment?
Time to Pain Relief = ________
C. In assessing the association between gender and time to pain relief, is there evidence of confounding by age or severity? Briefly justify your answer.