Mark W. Vernoy,
Palomar College Diana J. Kyle,
Fullerton College
Correlation
Glossary
Coefficient of determination
is the effect size. It is the part of the variance of one variable that can be explained or attributed to the variance of a related variable. Coefficient of determination = r2
Correlation
is a relationship between two variables whereby a change in one variable is associated with a congruent change in the other.
Correlation coefficient
is a measure that indicates the relationship between two variables. The Pearson product moment correlation coefficient symbol is r and the range is -1.00 to +1.00. The sign of the coefficient indicates the direction of the relationship and the number indicates the size of the relationship.
A positive correlation represents the situation where both variables vary in the same direction and a negative correlation indicates a situation where the variables vary in opposite directions. A correlation coefficient near +1.00 or -1.00 is a large correlation, whereas a correlation close to 0 is small.
refers to a numerical value, according to the value of the degrees of freedom that is used as a decision point. In statistical analyses, critical values are based on the probability of a certain outcome occurring merely by chance. When the absolute value of the correlation coefficient is greater than the critical value, it is said to be statistically significant.
df = n - 2
Scatterplots
are a type of graph in which two sets of data are displayed, one along the abscissa and the other along the ordinate. The points are plotted where corresponding X and Y values intersect and show the direction and degree of correlation between two variables.