Explain the difference between a positive and a negative correlation, and the difference between a strong and a weak correlation between two variables.
Recognize that a bivariate distribution is plotted on a scatterplot (sometimes called a scattergram or a scatter diagram).
Recognize that correlations from 0 to about .50 are considered weak, from about .50 to .80 are considered moderate, and from .80 to 1.00 are considered strong. (Play with stronger, weaker, positive, negative correlations and their scattergrams)
Try changing data to show a stronger, weaker, positive, or negative correlation and its scattergram. (Click here and save the file)
Describe the relation between the size and strength of a correlation and the direction and spread of points in a scatter diagram; given a scatter diagram, decide whether the correlation is positive or negative, weak or strong.
Recognize a scatter diagram of a perfect correlation.
Describe the range of values of the Pearson correlation coefficient r, and the relation between the value of r and the size and strength of the relationship between the variables.
Given a calculational formula for r, calculate r for small sets of data to observe the effects of the relationships in the data on the correlation coefficient.
Use SPSS to calculate r for large sets of data.
Identify correct and incorrect interpretations of correlations.
Describe the effect on r of: