HPER-H 391
• Round numbers to two decimals unless otherwise noticed
• As the group under study becomes homogeneous on one or both variables. The absolute value of
the pearson correlation becomes smaller.
• Try to find a heterogeneous (diverse) sample.
• Size of group generally does not affect the size of the absolute value of r (pearson correlation)
• r= correlation coefficient
• Positive or negative correlation
• Magnitude
• 0.8-1.0 very strong
• 0.6-0.8 strong
• 0.4-0.6 moderate
• 0.2-0.4 weak
• 0-0.2 little
• r^2=coefficient of determination. This decimal needs to be multiplied by 100 to become a
percentage.
• This number is the percentage of variance in one variable that is accounted for in the
other variable.
• Interpreting r
• Ordinal not interval or ratio scales
■The difference between .2 and .4 is not the same as the difference between .6
and .8
• Correlation does not imply causality
• Nominal-nominal
■Gender+political preference
■Lambda, cramer’s V, Contingency coefficient
• Other correlations:
• Nominal-ordinal
