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Algebra 1

3.6.3 Using the Term Causal Relationship

Algebra 13.6.3 Using the Term Causal Relationship

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Activity

The phrases “correlation, not causation” or “association, not causation” are often used to refer to situations in which there is a relationship, but it is not a causal relationship. While correlation used to describe the strength of the relationship between variables, a causal relationship means that a change in one of the variables actually causes a change in the other variable.

Describe a pair of variables with each condition. Be prepared to show your reasoning.

1.

Two variables have a causal relationship.

2.

Two variables have an association in which the variables are strongly related, but a third factor might be the cause for the changes in the variables.

3.

The variables are not related.

4.

How are associations and causal relationships similar?

5.

How are associations and causal relationships different?

6.

How are associations and causal relationships different from data sets representing data that are not related?

Are you ready for more?

Extending Your Thinking

For 1 - 4, use the following instructions.

Look through news articles or advertisements for claims of causation or correlation. Find 2 or 3 claims and read or watch the articles or the advertisements. Answer these questions for each of the claims.
1.

What is the claim?

2.

What evidence is provided for the claim?

3.

Does there appear to be evidence for causation or correlation? Explain your thinking.

4.

Choose the claim with the least or no evidence. Describe an experiment or other way that you could collect data to show correlation or causation.

Self Check

Which of the following is a causal relationship?
  1. The lower the temperature, the more people go ice skating.
  2. The size of a deck and number of wood boards used.
  3. The temperature and number of people buying hot chocolate.
  4. The number of kids in a family and the number of pets in a family.

Additional Resources

Is It Causation?

Correlation means there is a relationship or pattern between the values of two variables. A scatter plot displays data about two variables as a set of points in the xyxy-plane and is a useful tool for determining if there is a correlation between the variables.

Causation means that one event causes another event to occur. Causation can only be determined from an appropriately designed experiment. In such experiments, similar groups receive different treatments, and the outcomes of each group are studied. We can only conclude that a treatment causes an effect if the groups have noticeably different outcomes.

Why doesn’t correlation mean causation?

Even if there is a correlation between two variables, we cannot conclude that a change in one variable causes a change in the other. This relationship could be coincidental, or a third factor may be causing both variables to change.

Example

Liam collected data on the sales of ice cream cones and air conditioners in his hometown. He found that when ice cream sales were low, air conditioner sales tended to be low, and that when ice cream sales were high, air conditioner sales tended to be high.

Liam can conclude that sales of ice cream cones and air conditioners are positively correlated.

Liam can’t conclude that selling more ice cream cones causes more air conditioners to be sold. It is likely that the increases in the sales of both ice cream cones and air conditioners are caused by a third factor, an increase in temperature!

Try it

Try It: Is It Causation?

Vivek notices that students in his class with larger shoe sizes tend to have higher grade point averages. Based on this observation, what is the best description of the relationship between shoe size and grade point average?

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