Last Update: 8/7/2015
When the x values for the datasets are different it's likely that the starting value of X (Xmin) and ending value of X (Xmax) of each curve will be different. You may want to average these curves in a specific range, such as a common range for the curves, or a full range from the smallest Xmin to the biggest Xmax of all curves.
This can be done by using Analysis:Mathematics:Average Multiple Curves tool. Select the desired X range from the Averaged X drop-down list.