A study of herpes zoster (shingles) was conducted among 140 outpatients seen in a dermatology clinic. Among patients over 50 with shingles, cataracts severe enough to require surgery, is often reported. In this study, thirteen percent of the patients over 50 had this type of cataracts, as compared with 3.8% of the general population over 50. Cataracts can be a complication of diabetes mellitus and a high incidence of diabetes is reported among shingles patients.

True or false:

(a) Diabetes is likely a confounder of the shingles-cataract association. (Assume no other sources of the following: bias, confounding, effect modification or measurement error) [ Select ] ["True", "False"]

(b) When comparing the prevalence of cataracts among individuals with shingles to the prevalence among those without shingles, not accounting for diabetes status would tend to cause the crude cataract prevalence ratio to underestimate the true prevalence ratio. (Assume no other sources of the following: bias, confounding, effect modification or measurement error). [ Select ] ["True", "False"]