If performance tends to come at uneven rates, you won't know how much better or worse you are doing by you age or grade or developmental scores. The terms are interchangeable. Scatterplots allow you to see the relationship between two variables. They consist of an axis for each of the variables with points marking the results of different individuals in the two variables. 65 or the blackboard for an example.
Direction describes whether there is a positive or negative relationship between the variables.
For instance, there might be a positive correlation between calorie intake and weight. And a negative correlation between the number of beers you have before a test and your score on the test. The strength of the correlation describes how well you can predict one variable knowing the other. The most common correlation coefficient is the Pearson Product Moment Correlation . This is often symbolized by an r.