Lecture 2: Variables

variables

characteristics of things of interest

variables of causation

independent, dependent, extraneous

independent

treatment; cause

dependent

outcomes; effect

extraneous

intervening; something unexpectedly having an effect

independent variable of constraint

very restrictive; manipulated by frequency, intensity, duration

dependent variable of constraint

not manipulated, but prescribed

extraneous variable of constraint

“controlling” for these in analyses

measurement levels of variables (values)

nominal, ordinal, interval, and ratio

nominal

name, classification, label; category matters; discrete

ordinal

rank ordered, on some dimension; order matters; usually discrete (both)

interval

rank ordered, on equal intervals; differences are relatively equal; continuous scale data

ratio

interval with absolute zero; zero = nonexistence; continuous scale data

continuous data

on some dimension/scale (infinite)

discrete data

limited values (finite)