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Flashcards in biostats Deck (11):
1

absolute risk reduction

ARR = event rate in control group - event rate in tx group

2

appropriate calculation for case-control study

odds ratio

3

appropriate calculation for cohort study

relative risk

4

odds ratio calculation

ad/bc

5

relative risk calculation

a/(a+b)/ c/(c+d)

6

attributable risk calculation

a/(a+b) - c/(c+d)

7

number needed to treat calculation

1/ARR

8

number needed to harm calculation

1/AR

9

confounding vs. effect modification

when confounding is controlled for it usually reveals no significant difference between groups unlike effect modification (outcome modified by presence of another factor)

10

Hawthorne effect

study subjects change their behavior if they become aware that they are being studied

11

Berkson's bias

selection bias created by choosing hospitalized patients as control group