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False-negative rate

As explained in Statistics Every Programmer Needs

The false negative rate is the proportion of actual positive instances that a classifier incorrectly identifies as negative.

The false-negative rate (FNR) measures the proportion of actual positive instances that a classifier incorrectly labels negative. It is calculated as FN / (FN + TP) × 100 and is the inverse of the true positive rate. section 5.2.4

Use the rate to:

  • Quantify how often a model misses actual positives. section 5.2.4
  • Compare missed-positive errors with false-positive errors when their consequences differ. section 5.2.4
  • Evaluate logistic-regression classification alongside accuracy, true-positive rate, and other performance measures. section 5.3

Raisin classification

The classifier produced 66 false negatives and 384 true positives, so FNR = 66 / (66 + 384) × 100 = 14.67%. Thus, it missed about 15% of actual positive instances. section 5.2.4

Table 5.1 Confusion matrix for raisin classification. A confusion matrix stores classification metrics from a regression with actual and predicted binary outcomes.
Predicted
Kecimen (0)
Besni (1)
Actual
Kecimen (0)
tn
fp
Besni (1)
fn
tp

Read false negatives and true positives from the actual-versus-predicted confusion matrix before calculating the rate. section 5.2.4

How Statistics Every Programmer Needs covers it

How deep it goes
Defines the formula, relates FNR to true positive rate, and works through a confusion-matrix calculation.
Examples
Uses raisin-classification counts of 66 false negatives and 384 true positives to obtain a 14.67% rate.
What it assumes
Assumes binary actual and predicted outcomes, while using the confusion matrix to identify false negatives and true positives.
What you can do after
Diagnose missed-positive errors and compare their practical severity with false-positive errors during model evaluation.
How it connects
Connects false-negative rate with confusion matrices, true positive rate, false positive rate, accuracy, and ROC curves.

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This explainer was generated by Manning's knowledge graph from the text of Statistics Every Programmer Needs. The section links point to the parts of the book it draws on.