# W3 - Descriptive Statistics Flashcards

Define nominal scale

Subjects grouped into mutually exclusive categories.

Examples of nominal scale

Eye colour

Year of birth

Define ordinal scales

Ranks subjects/scores in order.

Doesn’t indicate how much better 1 score is to another.

Example of ordinal scales

University rankings

Define interval scales

Equal units or intervals between data points on a scale, but there’s no zero point.

Example of interval scales

Temperature

Define ratio scales

Equal units of measurement

Established 0 point.

Example of ratio scales

Mass

Length

Height

What are measures of central tendency used for?

To summarise or provide meaning to a whole dataset

To provide a ‘central’ value

What doesn’t central tendency show?

Distribution of scores

What is the SD?

Avg distance away from mean

What allows you to summarise data?

Measures of central tendency + dispersion

What graph would you make if you had a lot of data?

Frequency distribution plot/graph

Properties that all normally distributed data show

Symmetrical

Equal mean, median + mode

What do Z-scores do?

Describes a values relationship to the mean of a group of values.

How is the z-score measured?

In terms of SD from the mean

Equation to calculate z-score

(X - mean) / SD

Where would z-score of 0 be on a normal distribution curve?

In the middle of the bell curve