Medical Application of Stats

Special Terms and Definitions:

Prevalence - total number of cases with a disease in a population at a given time

Simple Example:

-100 patients with disease out of a population of 200
prevalence is 100/200 = 50%

• True positive - someone who tests positive for a disease and actually has the disease
• False Positive - someone who tests positive for a disease but does not have the disease
• False negative - someone who tests negative for a disease and actually has the disease
• True negative - someone who tests negative for a disease and does not have the disease

Sensitivity - refers to the sensitivity of a test for people with the disease.

Definition: probability that a person with the disease will be correctly identified by a test for the disease

Specificity - refers to the sensitivity of a test for people without the disease: 

Definition: probability that a person who does not have the disease will be correctly identified

Double-blind study - neither the investigator nor the subject knows which subject is receiving an experimental treatment or control experience (e.g., drug versus placebo)

Reliability - reproducability of a test

Validity - whether a test truly measures what it purports to measure, refers to the appropriateness of a test's measurements

Meta-analysis - pooling results from several previous studies to achieve greater statistical power

Case-control study - observational study, samples chosen based on presence/absence of disease

Cohort study - observational study, samples based on presence/absence of risk factors and subjects followed over a period of time

Clinical trial - experimental study, compares therapeutic benefit of 2 or more treatments