1W change in call open interest is calculated as percentage change between current days call OI and the call OI 5 trading days ago. Suppose current day’s call OI is 120 and the call OI 5 trading days ago was 98, 1w change in call OI is 22.44% ((120/98) – 1)*100. 

A positive change in call OI indicates that more people have bought call contracts compared to 5 days ago. This suggests that participants are bullish on the stock. On the contrary if the output is negative it indicates that investors have squared off their open positions and are not confident about the future price rise.