Epi

Question 1

Cross sectional study is called a prevalence study because

Answer 1

It looks at one snapshot in time

Question 2

Attributable risk =

Answer 2

Incidence in exposed - incidence in unexposed

Question 3

Nnt=

Answer 3

1/attributable risk

Question 4

Relative risk=

Answer 4

Incidence in exposed/incidence in unexposed

Question 5

Odds ratio=

Answer 5

Odds that diseased person is exposed/odds that non diseased person is exposed

Question 6

Ppv=

Answer 6

Probability that pt with positive test result has the disease (a/a+b) where b is the false positives

Question 7

Npv=

Answer 7

Probability that pt with negative test result didn’t have the disease (d/c+d) where c is the false negatives

Question 8

When prevalence goes down, what happens to ppv and npv

Answer 8

Ppv goes down

Npv goes up

Question 9

What are case control studies

Answer 9

Looks at pp with and without dz and looks back to see whether they had an exposure or not

Question 10

P value of under ___ is statistically significant

Answer 10

0.05

Question 11

Type I(a) error

Answer 11

Probability of concluding there is a difference in treatment effects between groups when there is not

Question 12

Type II (B) error

Answer 12

Probability of concluding there is no difference in treatment effects when in fact a difference exists

Question 13

Power is the

Answer 13

Probability that a study will find a statistically sig difference when one is truly there

Question 14

Power=

Answer 14

1-type II(b) error

Question 15

Primary prevention

Answer 15

Preventative measures to decrease incidence of dz (exercise to prevent cv dz)

Question 16

Secondary prevention

Answer 16

Identifying dz early (eg routine mammograms)

Question 17

Tertiary prevention

Answer 17

Measures to decrease morbidity and mortality (tx of dz)

Question 18

Most common cause of cancer death

Answer 18

Lung

Question 19

Most prevalent cancers

Answer 19

Prostate and breast, then lung second and crc third

Question 20

Leading cause of death

Answer 20

Heart dz both sexes, followed by cancer

Question 21

1-specificity=

Answer 21

False positive rate

Question 22

Define npv and ppv

Answer 22

Ppv= prob of having the disease of the test is positive (nothing to do with sensitivity)

Npv=prob of not having dz of test is negative

Question 23

Difference between case control and retrospective cohort studies

Answer 23

Retrospective cohort: review past risk factors and compare resulting incidence of disease

Case control: look at diseased vs non diseased cases and compare past risk factor frequency

Question 24

Raising the cutoff point in a test will ___ specificity and __ sensitivity

Answer 24

Increase

Decrease

Question 25

Increase in prevalence ___ ppv And ___ npv

Answer 25

Increase ppv

Decrease npv

Question 26

Decrease in prevalence ___ ppv And ___ npv

Answer 26

Decrease ppv

Increase npv

Question 27

Two small z test and t test are used to compare

Answer 27

Two means

Question 28

Chi squared test is used to compare

Answer 28

Proportions (eg observed as proportion of expected)