1) An open label study (where participant are aware of the treatment they are taking) is conducted to assess the time 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 diseases (a score ranging from 0 t0 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= 3.8 +0.4 severity
Time to pain Relief = -19.8 +0.50 Age +10.9 male Gender +0.2 severity
What is expected time to pain relief for a male following treatment?
What is the expected time to pain relief for a participant aged 50 following treatment
2) A study is conducted in patients with HIV. The primary outcome is CD4 cell count which is a measure of the stage of the disease. Lower CD4 counts are associated with more advanced disease. The investigators are interested in the association between vitamins and mineral supplements and CD4 count. A multiple regression analysis is performed relating CD4 count to use of supplements ( coded as 1=yes, 0=no) and to duration of HIV in years ( i.e. the number of years between the diagnosis of HIV and the study date) for the analysis, y=CD4 count. Y=302 +15.1 supplements- 18.6 duration of HIV.
A) What is the expected CD4 count for a patient taking supplements who has had HIV for 2.5 years.
B) What is the expected CD4 count for a patient not taking supplement who was diagnosed with HIV at study enrollment?
C) What is the expected CD4 count for a patient not taking supplements who has had HIV for 2.5 years
3) A randomized trial is conducted to evaluate the efficacy of a new cholesterol lowering medication. The primary outcome is incident coronary artery disease. Participants are free of coronary artery disease at the start of the study…