Lower Threshold Power

I am new to Xert and was curious how the LTP was calculated. I am seeing a slow rise in this number over the x-axis (which is great), but would like to know how it is being calculated.
Thank you,

There was a bit of a discussion on LTP on the forum (apologies for the lack of search capability here). If you scroll down, you’ll see a similar question and discussion on this topic. There is also an entry in the glossary.