Explain what it means to have a correlation in a scatterplot.

A correlation exists in a scatterplot if there is a general trend in the outputs as inputs increase. If the outputs generally increase in value, then there is a positive correlation. If the outputs generally decrease in value, then there is a negative correlation.

Or:

The corelation in a graph is the where the clusters head to on a line. There is a positive and a negative corelation most of the time, and sometimes no corelation.