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Class probability distribution

As explained in Data Without Labels

A probability score is a numerical estimate between zero and one representing the predicted probability of a classification event.

A class probability distribution represents predicted probabilities for classification outcomes. A trained classification algorithm generates a probability score for an unseen case, with values between zero and one, before a final business decision. section 1.5.1

Use the scores to:

  • Distinguish binary outcomes such as churn or no churn, fraud or genuine, and pass or fail. section 1.5.1
  • Handle multiclass targets such as positive, negative, or neutral. section 1.5.1
  • Avoid treating unrestricted linear-regression outputs as probabilities, because they can fall below zero or exceed one. section 1.5.1

Telecom churn

A telecom operator trains on historical subscriber data containing revenue, service duration, average cost, monthly usage, and a churned yes/no target. The model produces a churn probability for each unseen customer, supporting the final retention decision. section 1.5.1

Figure 1.14 A linear regression model will not be able to do justice (left); hence, we have logistic regression for classification. Linear regression can generate probability scores more than 1 or less than 0 too, which is mathematically incorrect, whereas the sigmoid function generates probability scores between 0 and 1 only (right).
figure

Compare invalid linear-regression outputs with sigmoid-generated scores constrained between zero and one. section 1.5.1

How Data Without Labels covers it

How deep it goes
Defines binary and multiclass scores and motivates sigmoid-based outputs, without detailing model training or decision thresholds.
Examples
Uses telecom subscriber churn with revenue, service duration, average cost, and monthly usage as illustrative predictors.
What it assumes
Assumes familiarity with supervised learning and historical data, while introducing categorical targets and binary versus multiclass outcomes.
What you can do after
Apply probability scores to make final decisions for unseen classification cases.
How it connects
Connects supervised learning, classification algorithms, logistic regression, sigmoid functions, and categorical target variables.

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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Data Without Labels. The section links point to the parts of the book it draws on.