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Lære Choosing Calibration Methods | Applied Calibration Workflows
Model Calibration with Python

bookChoosing Calibration Methods

When you need to calibrate probabilistic predictions from a machine learning model, selecting the right calibration method is crucial. The main techniques you are likely to encounter are Platt scaling, isotonic regression, and histogram binning. Your choice should depend on the size of your dataset, the nature of your model’s miscalibration, and the complexity you can handle.

Platt scaling is a parametric method that fits a logistic regression model to the uncalibrated scores. It is particularly effective when the miscalibration can be corrected with a sigmoid-shaped curve. This approach is best when your dataset is small or when you expect the relationship between predicted probabilities and actual outcomes to be monotonic and roughly linear after transformation.

Isotonic regression is a non-parametric method that fits a monotonically increasing function to the data. It is more flexible than Platt scaling and can handle non-linear but monotonic miscalibration. However, it requires more data to avoid overfitting and is sensitive to noise in small datasets.

Histogram binning divides the predicted probabilities into discrete bins and calibrates each bin based on observed outcomes. This method is simple and can be robust even with moderate data, but it may not capture subtle patterns in the miscalibration.

Choosing the right method involves balancing bias and variance. Platt scaling introduces more bias but less variance, making it suitable for smaller datasets. Isotonic regression reduces bias at the cost of higher variance, so it is preferable when you have enough data and expect non-linear but monotonic miscalibration. Histogram binning offers a middle ground, being simple and interpretable but less precise for complex miscalibration patterns.

Small datasets with expected sigmoid (S-shaped) miscalibration
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Use Platt scaling. Its parametric nature prevents overfitting and works well when data is limited.

Large datasets with monotonic but nonlinear miscalibration
expand arrow

Prefer isotonic regression. Its flexibility can capture complex, monotonic calibration curves when enough data is available.

Models with unstructured or unknown miscalibration, moderate dataset size
expand arrow

Apply histogram binning. Its simplicity and robustness make it a good default when you are unsure about the miscalibration form.

Tree-based models or models with step-like miscalibration
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Histogram binning is often effective, as it aligns well with the discrete nature of predictions from tree ensembles.

When interpretability and simplicity are required
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Histogram binning provides easily explainable calibration adjustments.

1. Which calibration method is generally most suitable for small datasets?

2. If your model shows monotonic but nonlinear miscalibration and you have a large enough dataset, which calibration method should you choose?

question mark

Which calibration method is generally most suitable for small datasets?

Select the correct answer

question mark

If your model shows monotonic but nonlinear miscalibration and you have a large enough dataset, which calibration method should you choose?

Select the correct answer

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Sektion 3. Kapitel 2

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Can you explain when to use each calibration method in more detail?

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How do I evaluate if my model’s predictions are well-calibrated?

bookChoosing Calibration Methods

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When you need to calibrate probabilistic predictions from a machine learning model, selecting the right calibration method is crucial. The main techniques you are likely to encounter are Platt scaling, isotonic regression, and histogram binning. Your choice should depend on the size of your dataset, the nature of your model’s miscalibration, and the complexity you can handle.

Platt scaling is a parametric method that fits a logistic regression model to the uncalibrated scores. It is particularly effective when the miscalibration can be corrected with a sigmoid-shaped curve. This approach is best when your dataset is small or when you expect the relationship between predicted probabilities and actual outcomes to be monotonic and roughly linear after transformation.

Isotonic regression is a non-parametric method that fits a monotonically increasing function to the data. It is more flexible than Platt scaling and can handle non-linear but monotonic miscalibration. However, it requires more data to avoid overfitting and is sensitive to noise in small datasets.

Histogram binning divides the predicted probabilities into discrete bins and calibrates each bin based on observed outcomes. This method is simple and can be robust even with moderate data, but it may not capture subtle patterns in the miscalibration.

Choosing the right method involves balancing bias and variance. Platt scaling introduces more bias but less variance, making it suitable for smaller datasets. Isotonic regression reduces bias at the cost of higher variance, so it is preferable when you have enough data and expect non-linear but monotonic miscalibration. Histogram binning offers a middle ground, being simple and interpretable but less precise for complex miscalibration patterns.

Small datasets with expected sigmoid (S-shaped) miscalibration
expand arrow

Use Platt scaling. Its parametric nature prevents overfitting and works well when data is limited.

Large datasets with monotonic but nonlinear miscalibration
expand arrow

Prefer isotonic regression. Its flexibility can capture complex, monotonic calibration curves when enough data is available.

Models with unstructured or unknown miscalibration, moderate dataset size
expand arrow

Apply histogram binning. Its simplicity and robustness make it a good default when you are unsure about the miscalibration form.

Tree-based models or models with step-like miscalibration
expand arrow

Histogram binning is often effective, as it aligns well with the discrete nature of predictions from tree ensembles.

When interpretability and simplicity are required
expand arrow

Histogram binning provides easily explainable calibration adjustments.

1. Which calibration method is generally most suitable for small datasets?

2. If your model shows monotonic but nonlinear miscalibration and you have a large enough dataset, which calibration method should you choose?

question mark

Which calibration method is generally most suitable for small datasets?

Select the correct answer

question mark

If your model shows monotonic but nonlinear miscalibration and you have a large enough dataset, which calibration method should you choose?

Select the correct answer

Var alt klart?

Hvordan kan vi forbedre det?

Tak for dine kommentarer!

Sektion 3. Kapitel 2
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