Epidemiology 7/8 Flashcards Preview

Third year shit > Epidemiology 7/8 > Flashcards

Flashcards in Epidemiology 7/8 Deck (17):
1

what does the P value mean

probability of getting a result as extreme or more extreme if the null hypothesis is true (i.e.. no difference)

2

when do we reject null hypothesis

P less than or equal to 0.05

3

T/F: P values measure how likely study hypothesis is true

FALSE

4

What is a confidence interval

a range of values that could be plausibly generated by the sample

5

When you want to be more "confident" what occurs with the confidence interval?

It gets wider so you can capture the true value more often

6

define sensitivity

how well does a test correctly identify those with a disease (TP/all with disease)

7

specificity

how well a test correctly identifies those WITHOUT a disease (TN/all without disease)

8

PPV

of those that test positive, what proportion actually have disease

9

NPV

of those who test negative, what proportion actually don't have the disease

10

What happens to sensitivity/specificity/PPV/NPV when prevalence changes

Sensitivity/specificity don't change
-PPV increases with increasing prevalence, decreases with decreasing prevalence
-NPV decreases with increasing prevalence and increases with decreasing prevalence

11

Receiver Operating characteristic

describes intrinsic accuracy of a test considering various threshold changes

- larger area under curve indicates greater discriminating ability of test

12

number needed to treat/screen (NNT/NNS)

what is the impact of the treatment
- number of ppl you need to treat/screen to prevent 1 bad outcome

13

What does a higher NNT mean

increased number needed to treat = less effective test

14

Case-control study

select ppl with/without disease or outcome. Compared with controls regarding past exposures

15

Cohort study

select ppl with exposure/not but are initially free of the outcome. Followed and assess incidence of outcome in both exposure groups

16

ODDS Ration

Odds of disease in exposed/odds of dz in non-exposed

(ad/bc)

17

main difference between cohort and case-control study

start with exposure in cohort and outcome in case-control