Non-linear Regression
What is non-linear regression?
- You have already seen that linear regression is when you can use a straight line to fit bivariate data
- Non-linear regression is when you can use a curve (rather than a straight line) to fit bivariate data
- In your exam the regression could be:
- Linear:
- Quadratic:
- Cubic:
- Exponential: or
- Power:
- Sine:
How do I find the equation of the non-linear regression model?
- Using your GDC:
- Type the two sets of the data into your GDC
- Select the relevant model
- The exam question will tell you which model to use
- Your GDC will calculate the constants
- You can use logarithms to linearise exponential and power relationships
- Power: then
- and will have a linear relationship
- Exponential: then
- and will have a linear relationship
- Power: then
Examiner Tip
- You can use your GDC to plot the scatter diagram and include the graph of a regression model
- This will allow you to get a sense of how well the model fits the data
Worked example
Scarlett and Violet collect data on the length of a film ( minutes) and the audience rating ( %).
75 |
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83 |
75 |
51 |
38 |
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76 |
91 |
70 |