Stat Tools

Poisson Rate Test

Analyse PhaseGB

Test whether an observed defect/event rate differs significantly from a target (one-sample) or from another process (two-sample). Uses exact Poisson probability for one-sample and score test for two-sample.

Input

H₀: Observed rate = Target rate. H₁: Observed rate ≠ Target rate (two-tailed exact test).

Results

Observed rate is significantly different from target (p < 0.05)

Observed Rate

0.047000

Target Rate

0.040000

p-value

0.000000

Significant?

Yes (p < 0.05)

Rate 95% CI Low

0.035313

Rate 95% CI High

0.062555

p (less)

0.880417

p (greater)

0.000000

When to Use This Test

One-Sample Poisson Test

Use when you have a count of events over a time period or number of units, and want to compare to a known or target rate. Examples: defect counts per shift, hospital readmissions per 1000 patients, machine failures per month.

Two-Sample Poisson Test

Use when comparing defect rates between two processes, time periods, or machines. The test accounts for different observation windows (time or units). Example: Line A had 47 defects in 1000 units vs Line B had 62 defects in 1200 units.

MBB Coach

Hi! I'm here to help you choose the right tool and interpret your results.

Master Black Belt Coach — Poisson Rate Test
Guidance only · No data shared

Guidance only — your analysis data stays in your browser. Nothing is sent to AI.