PRACTICE WORKSHEET: RELIBILITY, VALIDITY, AND BIAS
1. A study was done to determine the effects of breathing coal dust in underground mines on developing lung cancer in non-smoking males. The study population consisted of male coal miners between the ages of 20 and 60 who do not smoke. Which is the best control population?
A. Males between the ages of 20 and 60 who do not work in coal mines and who do not smoke
B. Males between the ages of 20 and 60 who smoke 2-3 packs of cigarettes per day but do not work in coal mines
C.Males between the ages of 20 and 60 who smoke 2-3 packs of cigarettes per day and work in coal mines
2. Your patient is a 65 year old female with diabetes who must use a walker. She has 15 amalgam fillings that are between 30 and 50 years old. She wants to know if her amalgam fillings are going to increase her chances of having Alzheimer's disease. To answer her question you read an article that assesses the effects of amalgam fillings on urinary levels of mercury in healthy elementary school age children. Does this article have good external validity for your patient's question?
YES NO Explain your answer:
3. You want to determine if flossing is a daily part of oral hygiene in Detroit residents. You survey participants at the Detroit District Dental society annual meeting. Name one source of bias in this study.
4. A dentist wants to determine if a daily lunch of one peanut butter sandwich, one chocolate chip cookie, and one glass of chocolate milk in teenagers increases the prevalence of anterior root caries. He publishes a study of the treatment of one 13 year old male who presents to the dentist with root caries on tooth #7. Does this article have good internal validity to answer the dentist's question?
YES NO Explain your answer:
5. You administer a 10 question survey to high school students on September 22, 2012 about the effects of smoking on oral health. You give the same survey to the same students on April 10, 2013. When you compare both surveys you see that that the students gave essentially the same responses on both surveys. This shows good:
A. Internal validity
B. External validity
C. Reliability.