## Glossary of Behavioral Science from USMLE First Aid

### Deck Info

#### Description

#### Tags

#### Recent Users

#### Other Decks By This User

- Woman with anxiety about a gynecologic exam is told to relax and to imagine going through the steps of the exam.

What process does this exemplify? - Systematic desensitization.

- Large group of people is followed over 10 years. Every 2 years, it is determined who develops heart disease and who does not.

What kind of study is this? - Cohort study.

- Girl can groom herself, hop on one foot, and has an imaginary friend.

How old is she? - Four years old.

- Observational study that choses samples based on presence or absence of disease; collects information about risk factors.
- Case control study.

- Observational study where sample is chosen based on presence or absence of risk factors. Subjects followed over time for development of disease.
- Cohort study.

- Pooling data from several published studies to achieve greater statistical power.
- Meta-analysis.

- Experimental study comparing therapeutic benefits of 2 or more treatments, or treatment versus placebo.
- Clinical trial.

- Selection bias
- Nonrandom assignment to a study group.

- Recall bias
- Knowledge of presence of disorder alters recall by subjects.

- Sampling bias
- Subjects are not representative of the group; therefore results are not generalizable.

- Late-look bias
- Information is gathered at an inappropriate time.

- Prevalence of disease
- P = total cases at one time / total population

- Incidence of a disease
- I = new cases over a given time / total population AT RISK during that time

- Sensitivity
- Number of true positives divided by number of all people with the disease.

Probability of a positive test given that a person has the disease.

- False negative rate
- Equal to 1 - sensitivity.

- False positive rate
- Equal to 1 - specificity.

- Specificity
- Number of true negatives divided bynumber of all people without a disease.

Probability of a negative test given that a person is free of the disease.

- Positive predictive value (PPV)
- Number of true positives divided by the number of people who tested positive for the disease.

The probability of having a condition given a positive test.

- Negative predictive value (NPV)
- Number of true negatives divided by number of people who tested negative for the disease.

The probability of not having the condition given a negative test.

- Odds ratio (OR)
- [a][b]

[c][d]

OR = ad/bc

Odds of having disease in exposed group divided by odds of having disease in unexposed group.

Approximates relative risk if prevalence of disease is not too high.

Used for case-control studies.

- Relative risk
- [a][b]

[c][d]

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

Disease risk in exposed group divided by disease risk in unexposed group.

Risk is calculated within a group as number with disease divided by total number of people in group.

Used for cohort studies.

- Precision
- Precision is the consistency and reproducibility of a test (reliability); absence of random variation

- Accuracy
- Accuracy is the trueness of test measurements (validity)

- Null (Ho)
- Hypothesis of no difference

(There is no association between the disease and the risk factor in the population.)

- Alternative (H1)
- Hypothesis that htere is some difference

(There is some association between the disease and the risk factor in the population

- Type I error (alpha)
- Stating that there is an effect or difference when none exists

P is judged against alpha, a preset level of significance (usually <.05); where P is the probability of making a type I error