Mass Index on Gold

What it shows

A single line under the candles that idles near the Length setting. At the default of 10, quiet hours hold it near 10, and a burst of wider gold candles lifts it into a hump.

How Pravex works it out

1. Take each candle’s range: high minus low.
2. Smooth the range with a 9-candle EMA. Then smooth that EMA again with a second 9-candle EMA.
3. Ratio = first EMA ÷ second EMA. It is above 1 when ranges are widening quicker than the slower average, and below 1 when they are shrinking.
4. Mass Index = the sum of that ratio over the last Length candles.
5. A tidy case, not market data: if the ratio is 1.05 on each of the last 10 candles, the Mass Index is 10.5.

Settings

Setting	Default	What changing it does
Length	10	How many candles of the ratio are added up. A longer Length gives a bigger, steadier number that moves more slowly. The two 9-candle smoothings are fixed in the code and do not change.

How traders read it

Because the ratio hovers around 1, the sum hovers around Length. Read the line against its own level, not against a number from another chart. A rise well above the usual level says candle ranges are expanding.

The hump’s peak matters more than its height. When the line rolls over, the widening has stopped, and that often lines up with a pause or a turn. Which way is a question for the price chart, since the Mass Index never says.

No bands are drawn, so mark the last few humps on your own chart and judge each new one against them.

When it misleads

The Mass Index knows nothing about up or down, so a rise can come from a sell-off or a rally alike. On gold, a burst of wide candles, as often comes in the New York morning (the widest hours in our own measurements), makes the line jump, then it settles with no lasting signal. When ranges are small and steady, the line stays flat.

Questions and answers

Does a rising Mass Index mean price will fall?

No. It measures how quickly candle ranges are growing against their own slower average, and a rally widens candles as much as a sell-off does.

Does the 27 and 26.5 bulge rule work here?

Not at the default. Those numbers came with a 25-candle sum, which idles near 25. With Length 10 the line idles near 10, so set Length to 25 first if you want to use that rule.

Why does the Mass Index stay near 10 on my chart?

The ratio of the two EMAs hovers around 1, and the sum adds up 10 of them. Only sharp widening or shrinking of ranges moves it away.

Mass Index vs Bollinger BandWidth?

BandWidth measures the spread of closes around their average. The Mass Index measures how the high-low range of each candle is changing against its own average.

Related: Bollinger BandWidth, Choppiness Index, Ulcer Index, every indicator.