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Flashcards in epi/biostats Deck (26):
1

cross-sectional study

collects data from group to assess disease frequency, risk factors at a particular time. can show dz prevalence

2

case-control

compares a group with dz to group w/o dz, looks for prior event or risk factor. -> odds ratio

3

cohort

prospective or retrospective. compares a group with a risk factor/exposure to a group without to see if exposure is associated with incr. dz prevalence. -> relative risk

4

twin concordance

compares frequency of monozygotic and dizygotic twins developing same dz. -> heritability vs. environmental factors

5

adoption study

compares siblings raised by biological vs. adoptive parents. -> heritability vs. environmental factors

6

phase I trial

small n of healthy volunteers. -> safety, toxicity, pharmacokinetics, pharmacodynamics

7

phase II trial

small n of pts w/dz. -> treatment efficacy, optimal dosing, adverse effects

8

phase III trial

large n of pts, randomly assigned to tx vs. placebo. -> compares tx to standard of care

9

phase IV trial

postmarketing surveillance of pts after tx is approved. detects rare or long-term adverse effects.

10

sensitivity

= true positive rate. important for screening tests. = TP/(TP+FN) = 1-false neg rate. SN-N-OUT = highly sensitive, when negative, rules out dz

11

specificity

= true negative rate. important for diagnostic tests. = TN/(TN+FP) = 1-false positive rate. SP-P-IN = highly specific, when positive, rules in dz

12

positive predictive value

=proportion of positive results that are true positives. = TP/(TP+FP). PPV varies w/prevalence/pretest probability

13

negative predictive value

=proportion of negative results that are true negatives = TN/(TN+FN). NPV varies inversely w/prevalence/pretest probability.

14

incidence vs. prevalence

incidence = new cases (incidents). prevalence looks at all current cases. prevalence = incidence (almost) for short duration dz, e.g. common cold. prevalence + pretest probability (almost)

15

odds ratio

case controls. odds that the dz group has target exposure divided by odds that dz free group was exposed

16

relative risk

cohorts. risk of dz in exposed group divided by risk of dz in unexposed group.

17

attributable risk

difference in risk vetween exposed and unexposed groups

18

relative risk reduction

proportion of risk reduction attributable to intervention as compared to the control

19

absolute risk reduction

difference in risk (not proportion) attributable to the intervention as compared to a control

20

number needed to treat

number of patients who need to be treated for 1 patient to benefit = 1/ARR

21

number needed to harm

number of patients who need to be exposed to a risk factor for 1 patient to be harmed = 1/AR

22

type 1 error (alpha)

false positive error

23

type 2 error (beta)

false negative error

24

t test

compares mean of 2 groups

25

ANOVA

compares means of more than 2 groups

26

chi-square

compares 2 or more percentages or proportions of categorical outcomes, not means. chi-tegorical