Function TestSpec_PublicAPI_SampleVariance_SampleFormula

pkg/stats/spec_test.go:85–94

TestSpec_PublicAPI_SampleVariance_SampleFormula validates that SampleVariance uses the sample formula with N-1 as the denominator as described in the README.md. Specification: "SampleVariance: Returns sample variance (N-1 denominator)" Example: values [2,4,4,4,5,5,7,9] (N=8, mean=5, sum_sq_dev=32)

(t *testing.T)

//
// Example: values [2,4,4,4,5,5,7,9] (N=8, mean=5, sum_sq_dev=32) → sample variance = 32/7
func TestSpec_PublicAPI_SampleVariance_SampleFormula(t *testing.T) {
	var sv StatVar
	for _, v := range []float64{2, 4, 4, 4, 5, 5, 7, 9} {
		sv.Add(v)
	}

	expected := 32.0 / 7.0
	assert.InDelta(t, expected, sv.SampleVariance(), 1e-9,
		"SampleVariance should use N-1 (sample) denominator: sum_sq_dev / (N-1)")
}

// TestSpec_PublicAPI_StdDev validates that StdDev and SampleStdDev equal the
// square root of their respective variances as described in the README.md.