deltas are just another tool... and 1 to 15 is a misrepresentation...
typical delta data ranges from -15 to +15 and include 0
there are 3 main types of delta data I have in my spreadsheet...
1. Draw to Draw (difference of the numbers by position (sorted) from draw to draw) in draw-to-draw, 0's indicate a repeat. results are negative, 0's and positive integers.
2. Ball to Ball (differences between numbers in each position for one game) 0's indicate hitting a high or low limit... position 1 is that number -1 (how far the first position was from theoretical low limit of 1) for powerball, position 5 is 53-drawn number (theoretical high limit) all other positions are larger number-smaller number... all results are positive integers and 0's. spikes of 30 or more are not uncommon.
3. prediction to result (differences between your pick and the draw result, only useful if you pick a number based on a fixed repeatable formula, or one derived from stats... I use combinations of both)... 0's indicate hits. positive, negative and 0's occur... I use the most frequent delta number by position to do error correction.
a delta system is an empirical system prone to hindsight-induced false results. I use delta data to apply weights to my composite stat pick which is made up of 6 different sets of stats and 6 delta charts... the result is a weighted average based on past performance by position. I can't get a big hit so far, but I was right on the powerball 5 of the last 18 draws and I only play 1 line. It is paying for itself so far. I am doing better than when I would play 10 lines.
Bottom line is deltas can be incorporated into an overall strategy, but by themselves represent data just as random as the draw results... I would be skeptical of anyone selling a system based on deltas alone... all you need is excel to amuse yourslef for hours on end with deltas... I did.