Forest plots are an excellent way to convey a multitude of information in a single picture. Forest plots have become a recognized and well-understood technique of displaying several estimates concurrently, whether used to demonstrate various outcomes in a single research or the cumulative knowledge of an entire subject. This article investigates advanced uses of the forest plot with the goal of demonstrating Excel’s versatility in producing both basic and sophisticated forest plots. Forest plots are widely used to display meta-analysis findings. Unfortunately, no conventional forest plot graph option is available in Excel. In a meta-analysis, a forest plot is used to show the findings of many research in one figure.
The x-axis represents the value of the interest in the research (often an odds ratio, effect size, or mean difference), while the y-axis represents the findings of each particular study. This style of display makes it easy to see the findings of several research at once.
Creating a Forest Plot in Excel
The following step-by-step example illustrates how to make a forest plot in Excel.
Step 1: Enter the Data: First, we’ll enter each study data in the following format.
Step 2: Create a Clustered Bar Chart: Then, highlight the cells in the A2:B9 range. Click the Insert tab along the top ribbon, then the 2-D clustered bar option in the Charts section.
The horizontal bar chart shown below will appear:
Step 3: Add scatterplot Points: After that, we’ll create a new series called Points, that we’ll use to add scatterplot points to the graph:
After then, right-click anywhere on the plot and choose Data.
Step 4: Add Series: To add a new series, click Add in the select data source box that displays.
Then, leave the Series Name field empty and click OK. This will result in the addition of a single bar to the plot:
Step 5: Change Chart Type: Next, right-click the single orange bar and select Change Series Chart Type from the menu that appears. Change Series2 to a scatterplot in the new window that appears:
When you click OK, the chart will show a single scatterplot point.
Step 6: Update Series: After that, right-click the single orange spot and choose Data.
Click Series2 and then Edit in the box that displays.
For the x-values, use the cell range containing Odds Ratio, and for the y-values, use the cell range containing Points. Then press the OK button. The scatterplot points listed below will be included in the plot.
Step 7: Remove the Bars: Then, right-click on any of the plot’s bars and change the fill color to No Fill.
Then, on the right, double-click the y-axis and set the axis boundaries to a minimum of 0 and a maximum of 8.
Then, on the right, click and erase the y-axis. The following plot will be left.
Step 8: Add Error Bars: For Graph Lower, take the Odds Ratio – Lower 95% CI.
For Graph Upper, take the Upper 95% CI – Odds Ratio.
Step 9: Add Error Bars: Then, in the upper right corner of the plot, click the little green + sign. Check the box next to Error Bars in the selection menu. Then, on any of the points, click on one of the vertical error bars and select delete to remove the vertical error bars.
Then, under the selection next to Error Bars, select More Options. In the right-hand pane, enter the custom error bars to be used for the top and lower boundaries of the confidence intervals:
Step 10: Final Graph: As a result, As you can see, the chart resembles a forest plot: