What does “correlation” mean?

“There is a positive correlation between average family income and MCAS passing rate.”

“There is a negative correlation between family income and dental problems.”

“There is a positive correlation between income and education.”

“There is no correlation between shoe size and SAT scores.”

Can your group define or explain “correlation” with a picture or a few words?

Scatterplots for Correlation

Which picture shows income and education? Income and dental problems? Shoe size and SAT scores?

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Note! We have an x and a y here, but we aren’t asking whether x causes y.

What does “correlation” tell us?

Does a higher family income cause higher MCAS scores or do higher MCAS scores cause higher family income?

Could it be that something else makes income higher AND makes MCAS scores higher?

Can your group “ask questions, be willing to wonder,” think of “alternative explanations”?

What does “correlation” tell us?

Does a lower family income cause more dental problems or do more dental problems cause family income to fall?

Could it be that something else is caused by lower income AND causes dental problems?

Could it be that having a higher income causes something else to happen that prevents dental problems?

Can your group “ask questions, be willing to wonder,” think of “alternative explanations”?

What does “correlation” tell us?

Does education increase income or does income increase education? Could both be true?

Could there be something that causes both income and education to increase?

Could there be something that causes both income and education to decrease?

Can your group “ask questions, be willing to wonder,” think of “alternative explanations”?