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UWorld Step 2 > Stats Uworld + Notes > Flashcards

Stats Uworld + Notes Flashcards

1
Q

Meta-analysis is what kind of study?

T-test?

A

Pulls from multiple sources

Compares means (interval data) between 2 groups

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2
Q

1 SD means what?

2?

3?

A

68%

95%

99.7%

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3
Q

What is the SNNOUT/SPPIN mnemonic?

A

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

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4
Q

In what situations can the OR generally approximate the RR?

A

Rare diseases

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6
Q

LR(+) = ?

Always think what?

A

Sensitivity / (1 - specificity)

Sensitivity / specificity
Then manipulate the 1

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7
Q

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?

A

Both increase

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

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8
Q

High sensitivity test used for screening in diseases with what?

Specificity used for what?

A

Low prevalence

After a + screening test

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9
Q

Odds ratio means what?

A

1 # over 1 #

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10
Q

Cross-sectional study is what kind of study design?

Examines what?

A

Observational

Associations and prevalence

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11
Q

ARR = ?

A

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

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12
Q

Case control mnemonic?

A

CaDORF
Based on disease
Odds ratio
Risk factor frequency

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14
Q

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

A

Mean > median > mode

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15
Q

What is a cause of lead-time bias?

Occurs in what context?

A

Detecting the disease earlier

Develop a new test and says it is better

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16
Q

Odds ratio equation?

A

(ad) / (bc)

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16
Q

Loss to follow-up creates what kind of bias?

A

Selection bias known as attrition bias

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17
Q

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

A

Factorial

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18
Q

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

Question will ask you what?

A

ARP = (RR - 1) / RR

What % of blah blah blah

19
Q

Variance = ?

A

SD squared

20
Q

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

A

FP decreases

FN increases

21
Q
  • skew, what is the mean, median, mode like?
A

Mean < median < mode

25
Q

What is tertiary prevention?

Quarternary?

A

Treat disease support people w/it

Not repeating tests

26
Q

What is statistical power =?

A

1 - beta

27
Q

Relative risk equation?

A

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

27
Q

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

Describe it

A

Secondary

Screening for disease early to reduce impact

27
Q

Cohort mnemonic?

A

CoExRI
Based on exposure
Risk Ratio
Incidence

28
Q

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

A

Beta error (type 2)

29
Q

Incidence = ?

A

of new cases / # of people at risk

May have to subtract from denominator the people that have it

29
Q

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

A

Chi-square

30
Q

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

A

Length time bias

31
Q

CI formula = ?

A

mean +/- Z(SE)

Z = 1.96 for 95% CI
SE = SD x (sq RF of n)
32
Q

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

A

FN decreases

FP increases

33
Q

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

A

22.5

Take the average of 2 middle numbers

34
Q

Confounding bias means what?

How to control for it?

A

Some outside influence is related to the exposure and the outcome

Matching

34
Q

NNT = ?

A

1 / ARR

35
Q

How does increased prevalence effect PPV?

NPV?

A

Inc

Dec

35
Q

NNH = ?

A

1 / AR

36
Q

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

A

Alpha error (type 1)

37
Q

Cross-sectional study compares what?

A

Prevalence

CroP

39
Q

ANOVA compares what?

A

Compares means of 3 or more groups

A-NOV-A —> 3 syllables

43
Q

What is observer bias?

A

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

UWorld Step 2 (17 decks)

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