fix(ride): use effort metrics for moving time

2 files changed, 26 insertions, 4 deletions

diff --git a/cli/cli.go b/cli/cli.go
index d95f06f..d3aff22 100644
--- a/cli/cli.go
+++ b/cli/cli.go
@@ -135,7 +135,7 @@ func runBacktest(db *sql.DB) error {
 		fmt.Fprintf(table, "p%g\t%.1f\n", p, distribution[p])
 	}
 	table.Flush()
-	slog.Info("Moving time backtest", "rides", len(samples), "mean_err_pct", meanAbsErr(absErrors), "stderr_pct", stdErrAbsErr(absErrors))
+	slog.Info("Moving time backtest", "rides", len(samples), "mean_err_pct", math.Round(meanAbsErr(absErrors)*10)/10, "stderr_pct", math.Round(stdErrAbsErr(absErrors)*10)/10)
 	return nil
 }
 
@@ -144,7 +144,7 @@ func meanAbsErr(absErrors []float64) float64 {
 	for _, err := range absErrors {
 		sum += err
 	}
-	return math.Round(sum/float64(len(absErrors))*10) / 10
+	return sum / float64(len(absErrors))
 }
 
 func stdErrAbsErr(absErrors []float64) float64 {
@@ -154,7 +154,7 @@ func stdErrAbsErr(absErrors []float64) float64 {
 		sumSquares += (err - mean) * (err - mean)
 	}
 	variance := sumSquares / float64(len(absErrors)-1)
-	return math.Round(math.Sqrt(variance/float64(len(absErrors)))*10) / 10
+	return math.Sqrt(variance / float64(len(absErrors)))
 }
 
 func errorDistribution(absErrors []float64, percentiles []float64) map[float64]float64 {
@@ -169,7 +169,7 @@ func errorDistribution(absErrors []float64, percentiles []float64) map[float64]f
 		if index >= len(sorted) {
 			index = len(sorted) - 1
 		}
-		distribution[p] = math.Round(sorted[index]*10) / 10
+		distribution[p] = sorted[index]
 	}
 	return distribution
 }
diff --git a/cli/cli_test.go b/cli/cli_test.go
new file mode 100644
index 0000000..8290bce
--- /dev/null
+++ b/cli/cli_test.go
@@ -0,0 +1,22 @@
+package cli
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBacktestStatsUseUnroundedSamples(t *testing.T) {
+	absErrors := []float64{0, 0.1, 0.1}
+
+	assert.InDelta(t, 1.0/15, meanAbsErr(absErrors), 1e-12)
+	assert.InDelta(t, 1.0/30, stdErrAbsErr(absErrors), 1e-12)
+}
+
+func TestErrorDistributionUsesNearestRank(t *testing.T) {
+	distribution := errorDistribution([]float64{1, 2, 3, 4}, []float64{50, 75, 99})
+
+	assert.Equal(t, 2.0, distribution[50])
+	assert.Equal(t, 3.0, distribution[75])
+	assert.Equal(t, 4.0, distribution[99])
+}