The Volume Rate-of-Change ("ROC") is calculated
identically to the Price ROC, except it displays the ROC of the
security's volume, rather than of its closing price.
Interpretation
Almost every significant chart formation (e.g.,
tops, bottoms, breakouts, etc) is accompanied by a sharp increase in
volume. The Volume ROC shows the speed at which volume is changing.
Additional information on the interpretation of
volume trends can be found in the discussions on Volume and on the
Volume Oscillator.
Example
The following chart shows Texas Instruments and its
12-day Volume ROC.
When prices broke out of the triangular pattern,
they were accompanied by a sharp increase in volume. The increase in
volume confirmed the validity of the price breakout.
Calculation
The Volume Rate-Of-Change indicator is calculated by
dividing the amount that volume has changed over the last n-periods by
the volume n-periods ago. The result is the percentage that the volume
has changed in the last n-periods.
If the volume is higher today than n-periods ago,
the ROC will be a positive number. If the volume is lower today than
n-periods ago, the ROC will be a negative number.