More, courtesy of Neil Winston

Characteristics of Gaussian distribution patterns:
1. Pattern percentage - how many of the pellets in the shell end up in a 30-inch circle at 40 yards.
http://www.claytargettesting.com/Terms/pdfs/Pattern%20Percentage.pdf
2. Pattern Spread - how widely dispersed are they, as measured by 75% diameter.
http://www.claytargettesting.com/Terms/pdfs/SeventyFivePercentDiameter.pdf
3. Pattern concentration or "evenness" or "hotness" as measured by central thickening.
http://www.claytargettesting.com/Terms/pdfs/Central%20Thickening.pdf

Pattern patchiness
https://www.trapshooters.com/threads/pattern-board.824401/page-3

Shot stringing
https://www.trapshooters.com/threads/the-effect-of-a-shot-string-by-ed-lowry.58089/