Combining boxplots in Excel typically refers to displaying multiple data series or categories within a single Box & Whisker chart, allowing for easy comparison of their distributions. Excel's native Box & Whisker chart feature makes this straightforward, provided your data is structured appropriately.
Understanding "Combining" Boxplots in Excel
When you create a Box & Whisker chart in Excel, it's designed to represent the distribution of a set of numerical data for one or more categories. If your data includes distinct categories (e.g., different departments, product lines, or time periods) along with the corresponding numerical values, Excel will automatically generate a separate boxplot for each category on the same chart. This is how multiple "boxplots are combined" for comparative analysis.
Preparing Your Data for Combined Boxplots
To display multiple boxplots on a single chart, your data should be organized in at least two columns: one for the categories (the "Series" column) and one for the numerical values (the "Value" column). Each row should represent an individual data point, with its associated category.
Example Data Structure:
| Query (Series) | Seconds (Value) |
|---|---|
| A | 10 |
| A | 12 |
| A | 8 |
| B | 15 |
| B | 18 |
| B | 14 |
| C | 7 |
| C | 9 |
| C | 6 |
In this example, 'Query' serves as the category column, and 'Seconds' is the value column. When charted, Excel will generate a boxplot for Query A, another for Query B, and a third for Query C, all on the same chart.
Step-by-Step Guide to Creating Combined Boxplots
Once your data is prepared, follow these steps in Excel to generate a single chart with multiple boxplots:
-
Select Your Data:
- Highlight all the data you wish to include, ensuring you select both your "Series" column (e.g.,
Query) and your "Value" column (e.g.,Seconds). - Reference Point: This aligns with the first step from the provided reference: "1. Select the data in the Series and Value columns (Query and Seconds in this case)".
- Highlight all the data you wish to include, ensuring you select both your "Series" column (e.g.,
-
Insert the Chart:
- Navigate to the Insert tab on the Excel ribbon.
- In the "Charts" group, click on Recommended Charts.
- Go to the All Charts tab.
- Select Box & Whisker from the list of chart types.
- Click OK.
- Reference Point: This aligns with the second step from the provided reference: "2. Go to Insert - Recommended Chart - All Charts - Box & Whisker - OK."
-
Customize Your Chart:
- Excel will now display a Box & Whisker chart featuring a separate boxplot for each unique category present in your selected data.
- Change the Chart Title: Click on the chart title and type a meaningful name that accurately describes your data and comparison. For instance, "Query Performance Comparison."
- Reference Point: This aligns with the third step from the provided reference: "3. Change the Chart title to something meaningful."
- You can further customize your chart using the Chart Elements (
+), Chart Styles (brush), and Chart Filters (funnel) buttons that appear next to the chart. These options allow you to:- Add or remove chart elements like axis titles, data labels, and a legend.
- Change the chart's color scheme and style.
- Filter which categories or data points are displayed.
Practical Insights for Analysis
- Comparative Analysis: Combined boxplots are excellent for visually comparing the central tendency (median), spread (interquartile range), and outliers across different groups.
- Identifying Skewness: The position of the median line within the box and the length of the whiskers can indicate the skewness of the data distribution for each category.
- Outlier Detection: Individual points beyond the whiskers represent potential outliers, which are automatically plotted by Excel.
By following these steps, you can effectively "combine" multiple boxplots into a single, comprehensive visualization in Excel, facilitating robust data analysis and comparison.
