M4.7.6 For the adult
Scatter graphs and correlation
Mei measures the height and the arm span of 12 friends. Can a graph help her guess a friend's arm span from their height?
What this chapter teaches
A scatter graph plots two measurements for each person or thing as one dot. The pattern is correlation: positive, negative or none, strong or weak. A line of best fit helps estimate inside the range of the data. Correlation does not prove that one thing causes the other.
Three questions to ask
There is no one right wording. Listen for the idea.
- What does a scatter graph with dots falling from left to right tell us?
- Why is it risky to use a line of best fit far beyond the data?
- Ice creams sold and sunburn rise together. What could explain that, other than one causing the other?
After the chapter, the learner can
- Draw a scatter graph and a line of best fit
- Describe positive, negative or no correlation
- Explain why correlation does not prove one thing causes another
What they copy into their notebook
Scatter graph: one dot for each pair. Correlation: positive, negative or none. The line of best fit passes through the mean point. Use it inside the data. Correlation is not cause.