Lesson · M.2.3

The relationship between two variables

How to read a scatterplot for correlation, and tell an independent variable from a dependent one, the way TEAS data questions expect.

ObjectiveM.2.3Read2 minExam weightMeasurement and Data ≈ 47% of Mathematics

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What you will be able to do

  • Identify the independent and dependent variable in a paired data set.
  • Describe a scatterplot's trend as a positive, negative, or no correlation.
  • Distinguish correlation from causation when reading a scatterplot.

What the lesson concludes

  • The independent variable goes on the horizontal axis and is the one being changed or chosen; the dependent variable goes on the vertical axis and responds to it.
  • A positive correlation trends upward left to right; a negative correlation trends downward left to right; no correlation shows no clear pattern.
  • Correlation describes how two variables move together, it does not by itself prove that one causes the other.
  • Scatterplot questions are usually answered by eye, by describing the overall trend of the points, not by calculating anything.
  • Read the axis labels first so you know which variable is independent before you describe the trend.