Measuring Spam Filter Accuracy

Here are various schemes used to measure spam-filter accuracy. First, multiple-figure measurement schemes:

• FpFnPercentages: our favourite!
• BattingAverage: John Graham-Cumming's new system
• PredictiveValue: how the MDs do it
• PrecisionAndRecall: how text classifiers do it
  

Single-figure measurements:

• TotalCostRatio: Ion Androutsopoulos' scheme
  

And measurements across a range of thresholds:

• RocGraphs: the radar operator's favourite