CH 5

Question 1

what is the purpose of the descriptive study?

Answer 1

identify and count cases of the disease in the population according to person, place, and time, and conduct sample studies

Question 2

what is a case report? case series?

Answer 2

• case report: report on 1 patient
• case series: report on a group of people

Question 3

what are case report and series are useful for? limitations?

Answer 3

useful for:
- recognition and description of new diseases, new manifestations of a disease
- detection of drug side effects
- provide insight into disease mechanisms
- provide info to help create a hypothesis
limitations
- no explicit comparison groups

Question 4

what are ecological studies?

Answer 4

• a study that examines rates and disease about a population-level factor
• a unit of observation is the group (country, state, neighborhood) rather than the individual
• exposure and outcome data at group level

Question 5

what P-value is significant?

Answer 5

</= 0.05

Question 6

what are the limitations of ecological studies?

Answer 6

• can’t adjust for confounding factors (can not account for other factors)
• complex relationships can be masked
• ecological fallacy: group level associations may not transfer to the individual level
• issues with suing prevalent cases: prevalence is not ideal of Etiological research because it combines incidence and duration

Question 7

what are the strengths of ecological studies?

Answer 7

• inexpensive and fast - conducted on available data
• good for the early stage of knowledge
• a wider range of exposures (especially for international studies) than other types of studies
• might want to study the ecological relationship
• analysis is easy using a creation coefficient (r) or linear regression

Question 8

what are cross-sectional studies and surveys?

Answer 8

• a study/survey that examines the relationship between an exposure and disease at a single point in time
• takes a snapshot
• measures exposure prevalence in relation to disease prevalence
• many surveys are cross-sectional

Question 9

what are the limitations of cross-sectional surveys?

Answer 9

• problem with inferring temporal sequence of exposure and outcome (which came first)
• problematic when exposure is a changeable characteristic (smoking)
  -prevalent cases tend to be cases of longer duration which might e biased

Question 10

strengths of the cross-sectional survey? when is it fine for exposure to be a characteristic?

Answer 10

• quick and inexpensive
• highly generalized if based on general pop (gov surveys)
• problem with temporal inference can be avoided for inalterable, long-term and historical exposures
• fine for immutable characteristics (genetic testing/blood type), measures of long-term exposure (lead in bone), and historical exposure (activity over past 30 years

Question 11

what is the purpose for analytic cases?

Answer 11

compare groups and systematically determine if there is a comparison

Question 12

define crude?

Answer 12

rates or risk based on raw data `

Question 13

crude all-cause mortality rate

Answer 13

the total number of deaths from all causes per 100,000 pop

Question 14

direct standardization

Answer 14

• limitation of trying to compare crude rates—calculated for different populations—directly is that the
  populations may differ in structure by other factors such as age. A method that allows researchers to
  compare different populations that differ by factors such as age