Epidemiology

Question 1

validity

Answer 1

how close results are to true value

Question 2

reliability

Answer 2

if u repeat the experiment, how similar will ur results be to each other

Question 3

type 1 error

Answer 3

reject null hypothesis when it should be accepted-think it has an effect wen actually it doesn’t

Question 4

type 2 error

Answer 4

accept null hypothesis when it should be rejected (is false)-ur saying it doesn’t have an effect wen in fact it does

Question 5

prevalence

Answer 5

no of existing cases in one particular pnt in time

Question 6

incidence

Answer 6

occurrence of new cases over time period

Question 7

• Cumulative incidence

Answer 7

new cases over a specific period

Question 8

• Fatality

Answer 8

frequency of deaths

Question 9

• Validity

Answer 9

how close to the true value

Question 10

• Reliability

Answer 10

if u repeat the experiment lots of times, u will get the same result if reliable

Question 11

T test

Answer 11

compares means from 2 groups

measures continuous data

Question 12

chi square test

Answer 12

• association bw 2 categorical variable exposure n outcome
• (e.g. smoking [Y/N] vs. lung cancer [Y/N])
• for categorical variable (

Question 13

Correlation & Linear Regression:

Answer 13

linear relationship between two continuous variables (e.g. age and knee cartilage volume.)

Question 14

Logistic Regression:

Answer 14

Outcome = binary (Y/N event). Output = OR.

Question 15

Survival Analysis:

Answer 15

“time to event” analysis – outcome is 
continuous time

Question 16

diagnositic test vs screening test

Answer 16

screening= mass testing, see if unsymptomatic/apparently healthy ppl have disease

diag= • tests those who are likely to get disease (ie from screening/from symptoms). confirms if someone has a disaease or not

Question 17

true +ve

Answer 17

have disease n test positive

Question 18

true -ve

Answer 18

no disease n test negative

Question 19

false +ve

Answer 19

no disease but test positive

Question 20

false -ve

Answer 20

have disease but test negative

Question 21

sensitivity

Answer 21

true positive/total diseased

Question 22

specificity

Answer 22

true negative/total non-diseased

Question 23

PPV (positive predictive value)

Answer 23

true positive/total positive (i.e. probability person has disease wen test positive

Question 24

NPV (negative predictive value)

Answer 24

true negative/total negative (i.e. probability don’t have disease wen test negative)

Question 25

sensitivity n specificity

Answer 25

dont change with prevalence of disease

Question 26

PPV n NPV

Answer 26

change with disease

PPV low wen prevalence low

NPV high wen prevalence low