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Multiple Data Columns

When you have multiple measurement columns, each can have its own specification limits. Quantum XL creates a separate Cpk histogram for each column, letting you assess capability across different measurements.

Goal

Assess process capability for both Diameter (LSL = 9.5, USL = 10.5) and Length (LSL = 24.5, USL = 25.5) measurements.

Sample Data

Press Copy for Excel, then paste the table into a blank worksheet.

Diameter	Length
9.82	25.1
10.05	25.4
9.97	24.8
10.12	25.6
9.91	25.2
10.08	25.0
9.88	24.9
10.15	25.3
9.95	25.5
10.03	25.1

Each row contains paired measurements of Diameter and Length. Each column has different specification limits reflecting different tolerances.

Steps

1. Put the data in Excel

   Press Copy for Excel above the table, click cell A1 in a blank worksheet, and press Ctrl+V. The header row lands in row 1 and the 10 data rows in rows 2 through 11.

2. Launch the analysis

   From the Excel ribbon, select QXL Stat Tools → Analysis Tools → Create Histogram.

3. Select your data

   Select cells A1:B11 (the header row plus all 10 data rows across both columns).

4. Configure the analysis

   In the Cpk/Histogram dialog:

   • Data Columns: "Diameter" and "Length" should both be checked
   • Specification Limits for Diameter: LSL = 9.5, USL = 10.5
   • Specification Limits for Length: LSL = 24.5, USL = 25.5

   Click Finish to generate the charts.

Result

Quantum XL creates two Cpk/Histograms, one for Diameter and one for Length. Each has its own specification limit lines and capability statistics. Comparing the Cpk values reveals which measurement has better process capability relative to its specifications.