Enter your data for Poisson Capability Analysis

Stat > Quality Tools > Capability Analysis > Poisson

Enter your data

To specify the data for the analysis, complete the following steps.

  1. In Defects, enter the column of count data that you want to analyze.
  2. Under Sample size, select an option and specify the sample size:
    • Constant size: Enter a value to use as the same sample size for all samples.
    • Use sizes in: Enter a column that contains the size of each sample. This option allows you to specify samples of different sizes.
In this worksheet, Weak Spots contains the number of weak spots (defects) in each sample of wire. Length contains the length of wire for each sample.
C1 C2
Weak Spots Length
4 132
1 130
3 124
5 138

Historical μ (optional)

If you know the mean number of defects per unit in the population (μ), or if you have an estimate for your process from past data, enter a value to use for the analysis. If you enter a historical value, Minitab uses it to assess process capability.

If you do not enter a historical μ, Minitab estimates the proportion from your sample data and uses the estimate to calculate process capability.


If you have a target defects per unit (DPU) for your process, enter the value to use for the analysis. For example, if your process should not exceed 0.05 DPU, enter 0.05.

If you do not enter a target value, Minitab assumes that the target is 0 defects per unit.