Usmle Step 1 Dit: Behavioral Science

Front 1

Observational study that collects data from a group of people to assess a frequency of disease, at a particular point of time

Back 1

Cross-sectional study

Front 2

Can show disease prevalence, risk factor association with disease but noes not establish causality

Back 2

Cross-sectional study

Front 3

Observational and retrospective study that compares group of people with disease to a group without disease

Back 3

Case-control study

Front 4

Looks for prior exposure or risk factor, use Odds ratio (OR)

Back 4

Case-control study

Front 5

Compares a group with a given exposure or risk factor to a group without such exposure

Back 5

Cohort study

Front 6

Study that can be observational and prospective or retrospective

Back 6

Cohort study

Front 7

Looks to see if exposure or risk factor increase the likelihood of disease, use relative risk (RR)

Back 7

Cohort study

Front 8

Compares the frequency with which both monozygotic twins or both dizygotic twins develop same disease

Back 8

Twin concordance study

Front 9

Measure heritability and influence of environmental factors (nature vs nurture)

Back 9

Twin concordance study

Front 10

Compares siblings raised by biological vs adoptive parents

Back 10

Adoption study

Front 11

Experimental study involving humans, compares therapeutic benefits of 2 or more treatment, or of treatment and placebo

Back 11

Clinical trial

Front 12

Clinical trial study improves quality when study is

Back 12

Randomized

Controlled

Double blinded

Front 13

Drugs trial Phase I

Back 13

Small number of healthy volunteers

Purpose (is it safe)

Front 14

Drugs trial Phase II

Back 14

Small number of patients with disease of interest

Purpose (does it work)

Front 15

Drugs trial Phase III

Back 15

Large number of patients randomly assigned either to the treatment under investigation or the best available treatment

Purpose (is it as good or better)

Front 16

Drugs trial Phase IV

Back 16

Postmarketing surveillance trial of patients after approval

Purpose (can it stay)

Front 17

Neither patient nor doctor knows whether the patient is in the treatment or control group

Back 17

Double-blinded

Front 18

Random assignment to experimental group and control group

Back 18

Randomized

Front 19

Experimental group receives experimental treatment and control group receives placebo

Back 19

Controlled

Front 20

Proportion of all people with disease who test positive, or the probability that a test detects disease when disease is present

Back 20

Sensitivity (true positive rate)

Front 21

Proportion of all people without disease who test negative, or the probability that a test indicates non-disease when disease is absent

Back 21

Specificity (true negative rate)

Front 22

Proportion of positive test results that are true positive

Back 22

Positive predictive value

Front 23

Proportion of negative test results that are true negative

Back 23

Negative predictive value

Front 24

What is the formula of sensitivity

Back 24

=TP/ (TP+FN)

Front 25

If sensitivity is 100% TP/ (TP+FH) =

Back 25

1

FN=0, and all negatives must be TNs

Front 26

What is the formula of Specificity

Back 26

TN/ (TN+FP)

Front 27

If specificity is 100% TN/ (TN+FP)=

Back 27

1

FP=0, and all positives must be TPs

Front 28

What is the formula of Positive predictive value

Back 28

TP/(TP+FP)

Front 29

Positive predictive value varies directly with

Back 29

Prevalence and Pretest probability

Front 30

What is the formula of negative predictive value

Back 30

TN/(TN+FN)

Front 31

Negative predictive value varies inversely with

Back 31

Prevalence or pretest probability

Front 32

Test + and Disease +

Back 32

True positive

Front 33

Test + Disease -

Back 33

False positive

Front 34

Test - Disease +

Back 34

False negative

Front 35

Test - Disease -

Back 35

True positive

Front 36

How is incidence rate defined?

Back 36

Number of new casa in a specified time period / Population at risk during the same time period

Front 37

How is prevalence defined?

Back 37

Number of existing cases / Population at risk

Front 38

What is odds ratio?

Back 38

Odds that the group with disease was exposed to a risk factor (cases) divided by the odds that the group without disease was exposed. (controls)

Front 39

How is odds ratio calculated?

Back 39

a/c / b/d = ad/bc

Front 40

What is relative risk?

Back 40

Risk of developing disease in the exposed group divided by risk in the unexposed group

Front 41

Quantifying risk typically used in case-control studies

Back 41

Odds ratio

Front 42

Quantifying risk typically used in cohort studies

Back 42

Relative risk

Front 43

What is the relative risk reduction?

Back 43

The proportion of risk reduction attributable to the intervention as compared to the control

Front 44

How is relative risk reduction calculated?

Back 44

RRR = 1-RR

Front 45

What is attributable risk?

Back 45

The difference in risk between exposed and unexposed groups, or the proportion of disease occurrences that are attributable to the exposure

Front 46

How is relative risk calculated?

Back 46

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

Front 47

How is attributable risk calculated?

Back 47

AR = a/a+b - c/c+d

Front 48

What is absolute risk reduction(ARR)?

Back 48

The difference in risk attributable to the intervention as compared to a control

Front 49

What is the number needed to treat?

Back 49

Number of patients who need to be treated for 1 patient to benefit. Calculated as 1/ARR

Front 50

What is the number needed to harm?

Back 50

Number of patients who need to be exposed to a risk factor for 1 patient to be harmed. Calculated as 1/AR

Front 51

What is the mean?

Back 51

Sum of values/total number of values

Front 52

What is the median?

Back 52

middle value of a list of data sorted from least to greatest

Front 53

What is the mode?

Back 53

most common value

Front 54

What is the standard deviation?

Back 54

How much variability exists from the mean in a set of values

Front 55

What is the standard error of the mean?

Back 55

An estimation of how much variability exists between the sample mean and the true population mean

Front 56

How is the standard error of the mean calculated?

Back 56

SEM = SD/√n

Front 57

How is the graph shaped in normal distribution?

Back 57

Bell-shaped

Mean = medium = mode

Front 58

What is bimodal distribution?

Back 58

Nonnormal, suggests 2 different populations

Front 59

What is positive skew distribution?

Back 59

Nonnormal, Asymmetry with longer tail on the right.

Mean>median>mode

Front 60

What is negative skew?

Back 60

Nonnormal, asymmetry with longer tail on the left

Mean<median<mode

Front 61

Stating that there is an effect when one exists

Back 61

Correct result

Front 62

Stating that there is an effect when none exists (null hypothesis incorrectly rejected in favor of alternative hypothesis)

Back 62

Type I error

Front 63

Stating that there is not an effect when one exists (null hypothesis is not rejected when it is in fact false)

Back 63

Type II error

Front 64

How do you increase power and decrease the probability of making a type II error?

Back 64

Increasing sample size, increased expected effect size and increasing precision of measurement

Front 65

What is confidence interval (CI)?

Back 65

Range of values in which a specified probability of the means of repeated samples would be expected to fall

Front 66

When CI = 95%, Z = ...

Back 66

1.96 = 2

Front 67

When CI = 99%, Z =...

Back 67

2.58