We have used a learning algorithm to estimate a model's parameters from training data. How can we assess whether our model is a good representation of the real relationship? Let's assume that you have found another page in your pizza journal. We will use this page's entries as a test set to measure the performance of our model. We have added a fourth column; it contains the prices predicted by our model.
|
Test instance |
Diameter in inches |
Observed price in dollars |
Predicted price in dollars |
|
1 |
8 |
11 |
9.7759 |
|
2 |
9 |
8.5 |
10.7522 |
|
3 |
11 |
15 |
12.7048 |
|
4 |
16 |
18 |
17.5863 |
|
5 |
12 |
11 |
13.6811 |
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Several measures can be used to assess our model's predictive capability. We will evaluate our pizza price predictor using a measure called R-squared. Also known as the coefficient of determination, R-squared...
