Scales of Measurement

Nominal Scale of Measurement

Scale that only satisfies identity property of measurement. Descriptive category with no inherent numerical value (boys/girls; religion; political parties). Available math options: Counting and Mode (central tendency)

Ordinal Scale of Measurement

Scale that satisfies identity and magnitude. Each value has a unique meaning and an ordered relationship to every other value on the scale. It has an inherent rank (order) or the rank numbers have meaning. Numbers represent a quality being measured (identity) and can tell us if the item has more or less of the quality measured than another item (magnitude). Example: horse race. Rank order tells us which horses finished the race and in what order. We do not, however, know by how much the horses finished ahead or behind one another.

Interval Scale of Measurement

Scale that satisfies identity, magnitude and equal intervals. Fahrenheit scale is an example. Equal intervals (because the difference between 40 and 50 degrees is the same as the difference between 50 and 60. Zero is arbitrary and does not indicate absolute zero. This scale tells us not only bigger and smaller status but also by how much. An example is IQ scores.

Ratio Scale of Measurement

Scale that satisfies identity, magnitude, equal intervals and absolute/true zero. Weight of an object is an example. Money and annual income are examples.

Equal intervals

Scale units along the scale are equal to one another. the difference between 1 and 2 equals the difference between 19 and 20

Properties of Scales of Measurement

Each scale of measurement satisfies one or more of the following properties: Identity, Magnitude, Equal Intervals and Absolute Zero

Identity

Each value on the measurement scale has a unique meaning (boy or girl).

Absolute Zero

Properties of scale has a true zero point, below which no values exists.

Magnitude

Values have an ordered relationship to one another. Some values are larger and some are smaller.