Types of variables and levels of measurement

Ordinal numbers

________ represent the position in a group but not the distance between positions.

Variables

________ are identified events that change in value.

Ratio data

________: interval but include a real 0 and relative proportions.

Variables to be measured need precise operational definitions

the steps taken to measure the phenomenon and/or set of activities required to measure X

dependent variable

variable which is assumed to be directly affected by changes in the independent variable

independent variable

manipulated variable in an experiment which is assumed to have a direct effect on the dependent variable

an extraneous variable

any variable other than the independent variable which might have an effect on the dependent variable

Random variable/error

unpredictable and random variables that do not impact one condition more than another, e.g., feelings on the day tested, atmosphere of the room, temperature of the room

constant variable/error

variables which systematically impact one condition more than another, e.g., more interesting instructions, easier list of words, more practice

confounding variables

variable which is uncontrolled annd obscures any effect sought, usually in a systemic manner

The levels at which data can be measured are

nominal, ordinal, interval and ratio

Nominal data

simple classification

Ordinal data

cases are ranked or ordered

Interval data

intervals equal in amount

Ratio data

interval but include a real 0 and relative proportions