Biostats

Question 1

measures PREVALENCE of disease
Collects data from a group of people to assess the frequency of disease & related risk factors at a particular point in time

Answer 1

Cross-sectional study

observational

Question 2

Compares a group of people with disease to a group without a disease
Looks for prior exposure or risk factor
Measure: ODDS RATIO

Answer 2

Case-control study

observational & retrospective

Question 3

Compares a group with a given risk factor or exposure to a group without
Looks to see if exposure increases likelihood of disease
Measure: RELATIVE RISK

Answer 3

Cohort study

observational & prospective or retrospective

Question 4

nonrandom assignment to participate in a study group

Answer 4

selection bias
Includes sampling bias:
1. Berkson bias -> only looking at inpatients
2. Loss to follow-up
3. healthy worker and volunteer bias

Question 5

Awareness of the disorder alters the recall by subjects; common in retrospective studies

Answer 5

Recall bias

Question 6

Information is gathered in a way that distorts it

Answer 6

Measurement bias
Hawthorne effect: groups who know they are being studied behave differently -> use placebo control groups and blinding to fix

Question 7

Subjects in different groups are not treated the same

Answer 7

Procedure bias

Question 8

when a factor is related to exposure & outcome but not the causal pathway, it distorts or confuses effect of exposure on outcome

Answer 8

Confounding bias

Question 9

early detection is confused with increased survival

Answer 9

Lead-time bias

Question 10

measures of central tendency

Answer 10

Mean, median, mode

In the normal distribution, Mean = Median = Mode