Ontario MTH1W · Data · D1.3
Model two-variable data
Use a scatter plot and a line or curve of best fit to describe association and make cautious predictions.
The core idea
Two-variable data pairs two measurements. A trend can support an estimate, but association alone does not prove that one variable causes the other.
Learning example
Interpret a line of best fit
A model for study time x and quiz score y is y = 6x + 58. What score does it estimate for x = 4 hours?
- 1
Substitute x = 4 into the model.
- 2
y = 6(4) + 58 = 24 + 58.
- 3
The model estimates y = 82.
AnswerAn estimated quiz score of 82.
A common mistake
Calling 82 a guaranteed score. A line of best fit gives an estimate, and the model may have limitations.
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