Stat

BIOMEDICAL STATISTICS

Nature of Data

Qualitative - non-numeric or narrative in form

Quantitative - numeric, composed of numbers or scores. Examples of quantitative data include blood pressure, weight, age, etc.

Variable - a characteristic of an individual or group, e.g., body temperature, blood pressure, date of birth, or anything else that can be measured.

* Independent variable – presumed to influence the outcome; the one you have some control over/ can change. In experimental research, this is the variable that is manipulated, e.g., placebo vs. drug

* Dependent variable - the outcome of interest, assumed to be influenced by independent variables; the one you measure, e.g., whether or not a subject got cancer (independent variable might be whether or not the subject was a smoker), if the subject developed pneumonia or not (independent variable might be if he or she aspirated), or if a neonate is infected with HIV from the mother (the independent variable might be if the mother received AZT during her pregnancy)

* Discrete variables have a finite number of values between two points. Usually, discrete variables have only integers for values, e.g., number of children in a household, hospital readmissions, date of birth

* Continuous variables have, in theory, an infinite number of potential values between two points. Generally, a variable that has decimals or fractions is a continuous variable. Body temperature and pH are continuous variables.

Levels of Measurement

Nominal - grouping objects into classes. No "scale" is implied, e.g., nationality, gender, marital status, etc.

Ordinal - measures that indicate an order (i.e., the relationships can be expressed using > or <). The scale does not have equal intervals between the points, e.g., clinical nursing levels, socio-economic status, grades in the military, etc.

Interval - measures that indicate an order and have equal intervals between...