Exploring data

Outliers

A value in a data set that lies beyond the limits of the typical scores” (Vincent, 2005, p. 296).

Histogram

turns ratio or interval data into categorical data in order to observe the “distribution” of measurements.

Boxplots

These are also useful in determining the shape of a distribution and especially for identifying outliers

Standard scores examples

–Percentiles

–Z-scores

–T-scores

–Stanines

What are standard scores

A score that is calculated from a raw score that has a standard basis for comparison (e.g., the mean and the SD)

What do standard scores allow

The comparison of performance on different variables relative to the others in the population or sample.

Z-scores

Any individuals raw score can be expressed as the number of standard deviations away from the mean