Home / Statistical Tools / Analysis Tools / Dotplot / How-To / GroupBy
GroupBy¶
Use GroupBy to create separate dot plot charts for each group in your data, making it easy to compare distributions across shifts, departments, or locations.
Goal¶
Compare measurement distributions between Day and Night shifts to see whether one shift produces more variable results than the other.
Sample Data¶
Press Copy for Excel, then paste the table into a blank worksheet.
| Measurement | Shift |
|---|---|
| 24.2 | Day |
| 24.5 | Day |
| 24.8 | Day |
| 25.0 | Day |
| 25.1 | Day |
| 25.3 | Day |
| 25.5 | Day |
| 25.5 | Day |
| 25.8 | Day |
| 26.0 | Day |
| 26.2 | Day |
| 26.5 | Day |
| 27.0 | Night |
| 28.2 | Night |
| 28.5 | Night |
| 29.0 | Night |
| 29.5 | Night |
| 30.0 | Night |
| 30.5 | Night |
| 31.0 | Night |
| 31.5 | Night |
| 32.0 | Night |
| 33.5 | Night |
| 36.0 | Night |
Day shift has 12 observations and Night shift has 12 observations.
Steps¶
-
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 24 data rows in rows 2 through 25.
-
Launch the analysis
From the Excel ribbon, select QXL Stat Tools → Analysis Tools → Dot Plot.
-
Select your data
Select cells A1:B25 (the header row plus all 24 data rows).
-
Configure the analysis
In the Dot Plot dialog:
- Select the GroupBy radio button (instead of Excel)
- Data Columns: "Measurement" should be checked, "Shift" should be unchecked
- GroupBy: Move "Shift" to the GroupBy Order list
Click Finish to generate the charts.
How GroupBy Works
When you add a GroupBy column, Quantum XL creates a separate chart for every unique value in that column. In this example, the "Shift" column has two unique values ("Day" and "Night"), so we get two charts.
Result¶
Quantum XL creates two dot plot charts, one for each shift:
Day Shift: Twelve measurements tightly clustered between 24.2 and 26.5, showing a very consistent process.
Night Shift: Twelve measurements spread from 27.0 to 36.0, with a wider distribution and a higher center. The isolated dot at 36.0 stands out from the main group.
The two charts make it easy to see that the Night shift produces higher and more variable measurements than the Day shift.