Stats Uworld + Notes

Question 1

Meta-analysis is what kind of study?

T-test?

Answer 1

Pulls from multiple sources

Compares means (interval data) between 2 groups

Question 2

1 SD means what?

2?

3?

Answer 2

68%

95%

99.7%

Question 3

What is the SNNOUT/SPPIN mnemonic?

Answer 3

Highly sensitive test when Negative, rules OUT the disease
If you have a PAP smear that is negative, you can r/o cervical cancer

Highly specificity test when Positive, rules IN the disease
If you have a + Colposcopy, you probably have cervical cancer

Question 4

In what situations can the OR generally approximate the RR?

Answer 4

Rare diseases

Question 6

LR(+) = ?

Always think what?

Answer 6

Sensitivity / (1 - specificity)

Sensitivity / specificity
Then manipulate the 1

Question 7

If you have the 2 curves graph and then you move the 2 curves to make them smaller, what happens to specificity and sensitivity?

Why?

Answer 7

Both increase

Area of FN/FP is getting smaller when you smash the graph down

Question 8

High sensitivity test used for screening in diseases with what?

Specificity used for what?

Answer 8

Low prevalence

After a + screening test

Question 9

Odds ratio means what?

Answer 9

1 # over 1 #

Question 10

Cross-sectional study is what kind of study design?

Examines what?

Answer 10

Observational

Associations and prevalence

Question 11

ARR = ?

Answer 11

Event rate of control (in %) - Event rate of treatment (in %)

Question 12

Case control mnemonic?

Answer 12

CaDORF
Based on disease
Odds ratio
Risk factor frequency

Question 14

What is the relationship of mean, median, mode in + skew?

Answer 14

Mean > median > mode

Question 15

What is a cause of lead-time bias?

Occurs in what context?

Answer 15

Detecting the disease earlier

Develop a new test and says it is better

Question 16

Odds ratio equation?

Answer 16

(ad) / (bc)

Question 16

Loss to follow-up creates what kind of bias?

Answer 16

Selection bias known as attrition bias

Question 17

What kind of study utilizes 2 or more different interventions w/2 different variables studied independently?

Answer 17

Factorial

Question 18

What is the formula for Attributable risk % (ARP)?

Question will ask you what?

Answer 18

ARP = (RR - 1) / RR

What % of blah blah blah

Question 19

Variance = ?

Answer 19

SD squared

Question 20

On the graph with the curves, if they increase the cutoff value what happens to FP and FN?

Answer 20

FP decreases

FN increases

Question 21

• skew, what is the mean, median, mode like?

Answer 21

Mean < median < mode

Question 25

What is tertiary prevention?

Quarternary?

Answer 25

Treat disease support people w/it

Not repeating tests

Question 26

What is statistical power =?

Answer 26

1 - beta

Question 27

Relative risk equation?

Answer 27

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

Question 27

Checking BP at a health fair is what kind of prevention?

Describe it

Answer 27

Secondary

Screening for disease early to reduce impact

Question 27

Cohort mnemonic?

Answer 27

CoExRI Based on exposure Risk Ratio Incidence

Question 28

Study says no association but in reality there is one, what kind of error?

Answer 28

Beta error (type 2)

Question 29

Incidence = ?

Answer 29

of new cases / # of people at risk May have to subtract from denominator the people that have it

Question 29

Test shows 2x2 table and asks what kind of test is this?

Answer 29

Chi-square

Question 30

If a study is looking into diseases with a slowly progressive, BENIGN case, what type of bias are they worried about?

Answer 30

Length time bias

Question 31

CI formula = ?

Answer 31

mean +/- Z(SE) ``` Z = 1.96 for 95% CI SE = SD x (sq RF of n) ```

Question 32

On the graph with the curves, if they lower the cutoff value what happens to FP and FN?

Answer 32

FN decreases | FP increases

Question 33

Median of 20, 22, 23, 26 is what?

Answer 33

22.5 Take the average of 2 middle numbers

Question 34

Confounding bias means what? How to control for it?

Answer 34

Some outside influence is related to the exposure and the outcome Matching

Question 34

NNT = ?

Answer 34

1 / ARR

Question 35

How does increased prevalence effect PPV? NPV?

Answer 35

Inc Dec

Question 35

NNH = ?

Answer 35

1 / AR

Question 36

A study that says there is an association but in reality there is not, what type of error is this?

Answer 36

Alpha error (type 1)

Question 37

Cross-sectional study compares what?

Answer 37

Prevalence | CroP

Question 39

ANOVA compares what?

Answer 39

Compares means of 3 or more groups A-NOV-A —> 3 syllables

Question 43

What is observer bias?

Answer 43

Investigator’s decision is adversely affected by knowledge of the exposure status