Normalize advance-decline series for a common-scale comparison

Raw constructions do not share a visual scale

A standard advance-decline accumulation and an adjusted advance-decline ratio are not visually comparable in raw form even when both describe the same breadth tape. Advance-decline accumulation is a running construction that adds advancing and declining activity rather than expressing it as a centered ratio. An advance-decline ratio is a market-breadth ratio of advancing issues to declining issues, often recentered so moves above and below 1.0 are treated symmetrically.

Two indicator series can be placed on a shared 0-100 scale so their relative movement can be compared after unit differences are removed.

Center the ratio and apply exponential smoothing

Exponential smoothing is a recursive average that weights recent observations more heavily and is applied here to a breadth ratio over a stated lookback. A 19-day exponentially smoothed advance-decline ratio, adjusted so values above and below 1.0 receive equal weight, oscillates near +1.0 to -1.0 before that 0-100 remapping.

Remap each series as percent of range

Percent of range is a per-series remap that places each observation on a 0-100 scale using that series' own minimum and maximum. The remapping finds each series' own minimum and maximum, then restates each observation as 100 times its distance from the minimum divided by that series' range.

After both series are restated as percent of range and plotted against time, the previously incomparable breadth constructions can be inspected on one axis. Common-scale comparison plots the two remapped series on the same time axis so relative movement can be judged without mixing incompatible units. Separate 9-day and 40-day exponential averages of the adjusted ratio were shown as signal overlays on the same family of charts.