FOM 2.4.3 Flashcards
A study is conducted to determine the amount of people in the army with hearing loss. This is an example of what?
Prevalence
Men and women who had normal hearing during the first examination are given hearing tests two years later. The number of these soldiers that have new onset hearing loss is an assessment of what?
Incidence
What is observational vs experimental design?
Observational: examines conditions/events that already occurred or will occur anyways
Experimental: Conditions under the direct control of the investigator.
What is directionality and what is the difference between forward and backwards?
Forward directionality is moving forward in time to see how a disease develops
Backwards is starting with the disease and going back to see what the possible risk factors were
A non-directional study is often referred to as what?
Cross-sectional study
What is an example of cross-sectional study?
Urine BPA levels in relation to obesity in school-age children
Baseball players developing mucosal lesions with or without chewing tobacco
What are advantages of a cross-sectional study?
Convenient and inexpensive
Can evaluate several exposures/diseases
Can estimate population disease/ exposure
What are disadvantages of a cross-sectional study?
Cannot establish whether exposure preceded disease or disease influenced exposure
Can identify only prevalence but not incidence
May miss disease with short duration
What is an ecologic study?
Uses populations rather than individual people
What are advantages of Ecologic studies?
Pre-existing data may exist
May help generate a hypothesis
Useful in evaluating effects of interventions at population level
What is the main limitation of an ecological study?
Looks at the group overall and not individuals
What is a case-control study?
Working back to see a place of exposure. Starts with a disease then obtain a history of exposure to find a possible relationship Ex Heat Related deaths during 1999 heat wave in chicago
What are advantages of a case-control study?
Allows study of rarer diseases allows the study of several exposures at the same time.
What are disadvantages of case-control?
Subject to systematic error or bias
Does not allow for the study of several diseases
What is a cohort study?
Subjects are diesease free at baseline and must follow subject for an amount of time to see who develops a disease
What is a prospective cohort?
The cohort is assembled in the present and followed into the future?
What is a retrospective cohort?
The cohort is identified by past records and followed into the future
What are some advantages of a cohort?
Ability to establish incidence due to forward directionality
Less prone to bias
What are disadvantages?
Costly
Loss of subjects
Does not work with rare diseases
What are disadvantages of observational studies?
How to deal with extraneous difference between exposed and non-exposed groups to mimic experiment
Why is randomization critical in clinical research?
ensures the similarity of characteristics at start of comparison
Avoids bias on part of the investigator or patient
What are goals of randomization?
Study groups should be comparable on all levels except for exposure status
What is blinding and what are the levels of it?
Open, Single, and double
Degree of who knows what people are getting
What is open label blinding?
Patient and physician know treatment assignment
