Behavioral Science

Question 0

Case- Control Study

Answer 0

“retrospective study
Compares a group of people with the disease to a group of people without
Determines
- prior exposure of risk factor “what happened?”
- Odds ratio

Question 1

Cross Sectional Study

Answer 1

Assess the frequency of the disease at a point in time... "whats happening?" 
Determine: 
- risk factors
- disease prevalence 
- does not establish causality

Question 2

Cohort Studye

Answer 2

Prospective, and retrospective
Compares a group of people with a given RISK to a group of people without the RISK - determines if factor increases the risk-
- asks: “who will develop the diseasee” or “who has developed the disease?”
- determines the relative risk (RR)

Question 3

Twin Concordance Study

Answer 3

Measure the heritability and influence of environmental factors
“nature vs. nurture”
- compares the frequency with which monozygotic or both dizygotic twins develop the disease

Question 4

Adoption study

Answer 4

Compares siblings raised by biological vs. adoptive parents

- influence of heritability and influence of environmental factors

Question 5

Sensitivity

Answer 5

SN=TP/(TP+FN)

• The proportion of all people who have the disease that test positive
• high SN when FN is low, therefore all negatives must be TN–> RULE OUT!!
• used to RULE OUT if negative with a high sn (b/c person with disease is likely to be detected with a high sn)

Question 6

Specificity

Answer 6

TN/(TN+FP)= SP
1-FP= SP
- Measures the proportion of people who don’t have disease that actually test negative
- When SP is high, it means the FP is low– therefore all Positive tests must be TP –> RULE IN

Question 7

PPV (Positive Predictive Value)

Answer 7

Proportion of positive tests that are true positive - CORRELATES WITH PREVALENCE
TP/(TP+FP)=PPV

Question 8

NPV

Answer 8

proportion of negative tests that are actually negative - varies inversely with prevalence
NPV= TN/(TN+FN)

high pretest prob= low NPV

Question 9

Prevalence

Answer 9

Prevalence= # existing cases/# with risk factor
prevalence is the pretest probability
- related to a short term incidence (common cold)

Question 10

Incidence

Answer 10

Incidence= # of new cases/ # of people at risk

- NEW CASES synonymous with incidence

Question 11

Odds Ratio

Answer 11

(a/c)/(b/d)= ODDS RATIO

Odds that a person with the disease was exposed to a risk factor (a/c) compared to the odds that someone exposed to the risk factor does not have the disease (b/d)

Question 12

Relative Risk

Answer 12

Used in cohort studies
Risk of developing the disease in the exposed group (a/(a+b))/the risk of developing the disease in the unexposed group (c/c+d)
RR= a/(a+b) / c/(c+d)

Question 13

Attributable Risk

Answer 13

The DIFFERENCE in risk between the exposed group and the unexposed group

Question 14

Relative Risk Reduction

Answer 14

RRR= 1-RR

The PROPORTION of the RR attributed to the intervention as compared to the control

Question 15

Absolute Risk Reduction

Answer 15

The DIFFERENCE in risk attributed to the intervention (a/a+b) compared to the control (c/c+d)
ARR= (c/c+d)-(a/a+b)

Question 16

NNT

Answer 16

Number of pts needed to be treated in order to benefit

NNT=1/ARR

Question 17

NNH

Answer 17

Number of pts who need to be exposed to a risk factor to be harmed
NNH=1/AR

Question 18

Measures of Central Tendency

- mean, mode, median

Answer 18

Mean= total sum of all values/# of values 
Median= middle #
Mode= # that appears most often

Question 19

SD, SEM

Answer 19

SD= the variability from the mean set of values
1SD=68%
2SD= 95%
3SD= 99.7%

SEM= an estimate of how much variability exists between the sample population mean and the general population mean
SEM= SD/SR(N)