Apply the threshold rule at one half.

highlighted = computed this step

State the threshold rule

The rule is score greater than or equal to threshold gives class 1.

sty^=1s \ge t \Rightarrow \hat y=1
Decision Thresholds ExactlyExact score rows under two stated thresholds.same scored rows under two thresholdsthreshold 1/2score line, threshold 1/201t=1/2A4/5B3/5C2/5D1/5predictions at 1/2rowyscorepredA14/51B03/51C12/50D01/50confusion grid at 1/2cellcountTP1FP1FN1TN1threshold 3/4score line, threshold 3/401t=3/4A4/5B3/5C2/5D1/5predictions at 3/4rowyscorepredA14/51B03/50C12/50D01/50confusion grid at 3/4cellcountTP1FP0FN1TN2same four scored rows; rule is score at least thresholddoes not claim: NOT best threshold; NOT accuracy guaranteeNOT future performance; NOT calibration; NOT fairnessNOT safety; NOT generalization; NOT probability truth

Set threshold one half

At threshold 1/2, A and B are on or above the threshold marker.

t=1/2t=1/2
Decision Thresholds ExactlyExact score rows under two stated thresholds.same scored rows under two thresholdsthreshold 1/2score line, threshold 1/201t=1/2A4/5B3/5C2/5D1/5predictions at 1/2rowyscorepredA14/51B03/51C12/50D01/50confusion grid at 1/2cellcountTP1FP1FN1TN1threshold 3/4score line, threshold 3/401t=3/4A4/5B3/5C2/5D1/5predictions at 3/4rowyscorepredA14/51B03/50C12/50D01/50confusion grid at 3/4cellcountTP1FP0FN1TN2same four scored rows; rule is score at least thresholddoes not claim: NOT best threshold; NOT accuracy guaranteeNOT future performance; NOT calibration; NOT fairnessNOT safety; NOT generalization; NOT probability truth

Read the predictions

A and B get output 1. C and D get output 0.

y^=(1,1,0,0)\hat y=(1,1,0,0)
Decision Thresholds ExactlyExact score rows under two stated thresholds.same scored rows under two thresholdsthreshold 1/2score line, threshold 1/201t=1/2A4/5B3/5C2/5D1/5predictions at 1/2rowyscorepredA14/51B03/51C12/50D01/50confusion grid at 1/2cellcountTP1FP1FN1TN1threshold 3/4score line, threshold 3/401t=3/4A4/5B3/5C2/5D1/5predictions at 3/4rowyscorepredA14/51B03/50C12/50D01/50confusion grid at 3/4cellcountTP1FP0FN1TN2same four scored rows; rule is score at least thresholddoes not claim: NOT best threshold; NOT accuracy guaranteeNOT future performance; NOT calibration; NOT fairnessNOT safety; NOT generalization; NOT probability truth