Describing Scores on a Single Variable

With pictures:

frequency distribution; bar chart (histogram), line graph, bar graph

With numbers:

1. central tendency - mean; median; mode

2. variability/variation/dispersion —

range (sensitive to outliers)

sum of squares

variance Variance is the basis for inferential statistics such as t-test, F-test, and ANOVA.

standard deviation (original units)

(used to standardize scores)

3. skew (kurtosis)...

Transforming scores

standard(ized) scores - m = 0, s = 1 (z-scores)

Describing Scores in Two Variables

With pictures: scatterplot

With numbers:

association —

correlation — Pearson coefficient, r

variance accounted for

regression line

Correlation is the basis for inferential statistics such as multiple regression.