March 27-April 1
Measures of Dispersion
The amount of variation in a sample.
Range: Highest score minus lowest score.
Shows the influence of outliers.
Standard deviation: Measures the amount of variation around the mean.
Influenced by outliers.
Determines whether there is a relationship between two variables.
Note: determination of a relationship is not proof of causality.
Amount of Explained Variance
eta, Kendall’s tau-b, Spearman’s rho, Pearson’s r
Squaring shows how much the variation in one variable will explain variation in
the other variable.
Allows prediction of the second variable based on the score from the first.
Can a sample finding be used to estimate a characteristic of the whole
Stated as a probability level:
The probability that the results are not due to chance.
A Null hypothesis tests the significance of the bivariate association.
e.g. It states that there is no relationship between two variables, or that two
populations do not differ on some characteristic.
To test for statistical significance:
Set up a null hypothesis.
Establish an acceptable level of significance.
It must be .05 or lower (≤ .05).