Study Designs

Question 0

Case reports or case series

Answer 0

A single patient or a group of patients with a similar (unusual or rare) diagnosis

Question 1

Descriptive studies

Answer 1

Describes patterns of disease occurrence in relation to characteristics of person, place, and time. Used to formulate research questions but precludes ability to test hypothesis between exposure and disease

Question 2

Ecological studies (correlational studies)

Answer 2

Correlation between specific characteristics of a population and the occurrence of diseases are assessed. E and D are ascertained for groups (usually within geographic areas) rather than for individual subjects

Question 3

Studies of disease frequency

Answer 3

Studies that examine the change in frequency of disease (or death) with respect to time in different populations among different people

Question 4

Analytic studies

Answer 4

Designed to test etiologic hypothesis regarding E and D

Question 5

Observational (non-experimental)

Answer 5

Investigator observed E and D for individuals without intervention

Question 6

Cross-sectional

Answer 6

Investigator begins with a sample from a specified population and ascertains booth E and D at roughly the same time for each subject in that sample

Question 7

Cohort

Answer 7

Investigator begins by ascertaining E on persons without D, and then follows them for subsequent onset of D

Question 8

Case-control

Answer 8

Investigator begins with cases and non-cases of D and then ascertains past E status in both groups

Question 9

Intervention

Answer 9

Investigator intervenes by assigning E to subjects and then waits to observe events. E is randomly assigned