Graphic display of data communicates the nature of a distribution more quickly and vividly.

Scatterplot is arguably the most informative device for illustrating a bivariate distribution and visually assess correlation between two variables.

A scatterplot has two equal-length axes, one for each variable (“bivariate""). The horizontal axis of of figure below represents score values on the spatial reasoning test (X), and the vertical axis represents score values on the test of mathematical ability (Y). Each axis is marked off according to the variable’s scale.

Each dot, or data point, represents a student’s two scores simultaneously.

All you need to construct a scatterplot is graph paper, ruler, pencil, and a close eye on accuracy as you plot each data point. Consider the inspection of scatterplots to be a mandatory part of correlational work because of the visual information they convey.

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Sources:
Fundamentals of Statistical reasoning in Education, Theodore Coladarci, Casey D. Cobb, Edward W. Minium and Robert C. Clarke (Click for eBook)