Comparing Two Histograms in Excel

View Before and After Histograms Side by Side

It's hard enough to create one histogram using Excel's Data Analysis Toolpak much less two histograms side by side. But it's easy using QI Macros Histogram Template for Excel.

Creating Side by Side Histograms is Easy Using QI Macros

compare two histograms side by side

To use the side by side histogram template:

  1. Click on QI Macros Menu in Excel and select Capability Templates, Histogram with Cp Cpk:
  2. capability analysis templates

  3. Then select the second worksheet tab "Compare 2 Histograms":
  4. histogram template options

  5. Input the data and spec limits for both histograms in the yellow shaded input areas:
    • Histogram 1: data in columns A to E and spec limits in T1 and T2.
    • Histogram 2: data in columns F to J and spec limits in AD1 and AD2.

    input spec limits to compare two histograms

  6. To switch between sigma estimator formulas, change cell V2 to: 1) Pooled SD, 2) Sbar or 3) Rbar.
  7. The histograms with bell curves are created to the right. Right click on the Y axis to change minimum or maximum values if you want the scales to be the same.
  8. Process capability metrics Cp Cpk Pp Ppk are also calculated for comparison.

Overlaid Frequency Polygons

Found in our Compare Two Histograms template, a Frequency Polygon is a graph that is used to understand the actual shape of your distribution. Note that this is beneficial when you are comparing multiple data sets/multiple distributions.

It is created by placing a midpoint at the top of each bar/bin from your Histogram. A line is then drawn to connect the tops of said bar/bins, which represents the frequencies within your data set(s)/distribution(s):

Frequency Polygon

Comparing Histograms Example

Why Choose QI Macros to Perform Capability Analysis and Draw Histograms?



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