In Replacement for and Oil Price Radial Chart I used error bars as callouts, to connect labels to points on a line chart.
The technique is actually pretty simple. Here is the line chart, unadorned by any labels.
The data you need to label two points is shown below. The dates are the same as the corresponding line chart data points. The Y values (under “Labels”) are spaced above the line chart data points by the lengths of the error bars (under “Error Bar”).
Copy the first two columns of the data range shown above, select the chart, and use Paste Special to add the data as a new series.
Add custom negative Y error bars using the values in the table (see Error Bars in Excel Charts or Error Bars in Excel 2007 for assistance). Also, apply the labels in the last column of the range to this new series using Rob Bovey’s Chart Labeler.
Hide the added series (no markers and no lines), and format the error bars to remove the end caps.
With a lot of labels, I positioned the labels to the side of the hidden data points, as above. If it isn’t so crowded, you can center the labels above the points, below.
In an upcoming post, I’ll show how to add callouts using XY series to add line segments oriented at any angle, not just the horizontal or vertical line segments afforded by error bars.