The extent to which stress is a contributing factor to the severity of chronic illnesses was the focus of the study summarized in the following table (208). Seventeen conditions were compared on a Seriousness of Illness Rating Scale (SIRS). Patients with each of these conditions were asked to fill out a Schedule of Recent Experience (SRE) questionnaire. Higher scores on the SRE reflect presumably greater levels of stress. How much of the variation in the SIRS values can be attributed to the linear regression with SRE?

Use the following sums:

Admitting Diagnosis Average SRE, x SIRS, y Dandruff Varicose veins Psoriasis Eczema Anemia Hyperthyroidism Gallstones Arthritis Peptic ulcer High blood pressure Diabetes Emphysema Alcoholism Cirrhosis 130 317 231 325 816 563 312 603 405 599 357 21 173 174 204 312 393 454 520 621 636 733 776 824 1020 443 ophrenia Heart failure Cancer 772 17 yi = 8,517 17 17 = 7,973 17 ? = 4.611,291 =5.421.917 ! 17 Z Xy = 4,759,470 !