Link relatives = monthly or quarterly value / preceding monthly or quarterly value
Then we take averages of these link relatives. From these averages we calculate chain indicies.
Chain indicies = average of month or quarter * chain index of preceding month or quarter/ 100
For first quarter or month, we calculate two chain indicies. From these two indicies of first quarter or month, we calculate correction factor. Minus this correction factor from second quarter or month. Subtract twice of correction factor from third quarter or month and so on. In this way, we can get the seasonal incisies for each quarter or month.