In a study to determine the incidence of a chronic disease, 150 people were examined at the end of a three-year period. Twelve cases were found, giving a cumulative risk of 8%. Fifty other members of the initial cohort could not be examined; 20 of these 50 could not be examined because they died. Which source of bias may have affected the study?
A.Information bias: interviewer/abstractor bias
B.Hawthorne effect
C.Information bias: recall bias
D.Selection bias: survival bias
An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year:Number of skaters in Metroville during any given month 12,000
Roller-skating injuries in Metroville 600
Total number of residents injured from roller skating 1,800
Total number of deaths from roller skating 90
Total number of deaths from all causes 900The cause-specific mortality rate from roller-skating was:
A.
90/600 × 100,000
B.
90/1,800 × 100,000
C.
90/100,000 × 100,000
D.
90/900 × 100,000