The proportion of truly nondiseased persons who are so identified by the screening test

Specificity equation:

True negative/(false positive + true negative)

False-positive rate:

1 – specificity

False-negative rate

1 – sensitivity

What is positive predictive value?

The probability that a person with a positive test result has the disease

What is the positive predictive equation?

True positive/(true positive + false positive)

What is the negative predicted value?

The probability that a patient with a negative test result really is free of the disease

What is the negative predicted value equation?

True negative/(false negative + true negative)

Definition of prevalence:

The total number of cases of a given disease in a specified population at a designated time

Definition of incidence:

The number of new cases of a given disease during a given period in a specified population

What is the absolute risk reduction?

The absolute arithmetic difference in outcome rates between control and experimental patients in a trial

What is relative risk reduction?

The proportional reduction in outcome rates between control and experimental patients in a trial

A range of values that has a specified probability of containing the rate or trend:

Confidence intervals

A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment:

Double-blind method

The number of patients who need to be treated to prevent one adverse outcome:

Number Needed To Treat

The probability that an event will occur:

Risk

The number of units in a population to be studied:

Sample size

Mortality

The proportion of patients alive at some point after the diagnosis:

Survival

What is the null hypothesis?

Denoted by H_o; it is a proposal that there is no difference in a comparison.

What is a Type I error?

Rejecting the null hypothesis tested when it is true (α)

What is a Type II error?

Failing to reject the null hypothesis when a given alternative hypothesis was true (β)

The probability that the test will reject the hypothesis tested when a specific alternative hypothesis is true:

Power (1 – β)

Sum of all results divided by the number of results:

Mean

The middle value that divides the distribution of data:

Median

The most common value in data set:

Mode

The extent to which a test measures what it claims to measure:

Validity

The consistency with which the data collection process measures whatever it measures:

Reliability

An estimate of the population mean is:

Sample mean

What is central limit theorem?

For a large enough sample size n, the distribution of the sample mean will approach a normal distribution

What is standard deviation (SD)?