The data item is calculated as the percentage change in total traded volume between 5 trading days. Suppose the traded volume on Friday is 100 and on last Friday it was 170, 1W change in volume is calculated as (170/100) – 1*100 = 70%. A positive output indicates rising number of volume whereas a negative output indicates a drop in volume.
Change in volume needs to be viewed in conjunction with price change and open interest change. Rise in price accompanied by an increase in open interest and volume traded is a bullish signal. Rising price accompanied by falling open interest and volume as well as falling price accompanied by rising open interest and volume are both signals of a bearish trend.