Don't use that. Take the ratio between the gears. i.e. 14->15 is a ~7% gear reduction, 10->11 is a 10% gear reduction.

What you're calling "delta mechanical advantage" doesn't scale well for comparisons. It makes a given rear gear jump look bigger if you're in a bigger chainring, and it inflates the magnitude of jumps in the high part of the range compared with jumps in the lower part of the range. So a 46/10->46/11 jump is .418 and a 33/28->33/33 jump is .179, but your legs will feel the latter as a massively wider step, because it's an 18% reduction whereas the former is a 10% reduction.

Similarly, for plotting gear progression, you should use the log of the gear ratios so that jumps of the same ratio have the same size on the chart.