The fresh monthly quotes towards second webpage of the Grams.19 is actually determined regarding indication studies having fun with proportional interpolation. step one Proportional interpolation remedies next optimisation disease:

in which t = 0 ‘s the early in the day standard several months and you can t = T is the most recent or following standard several months. On top of that, , and are also the newest month-to-month guess and indication within day t, correspondingly, which can be the fresh standard from the go out t. Proportional interpolation decreases the sum of the squared differences between the newest ratio of your guess towards the signal in per month and you may the only prior, susceptible to the fresh restriction that imagine translates to the fresh new benchmark into the per standard period. The solution to which optimization problem is:

The fresh moves shown into 3rd webpage of your Grams.19 is determined as break-modified period-to-months changes in the latest related levels into the next web page. Streams is actually crack-modified in order to be the cause of transform otherwise discontinuities in supply research or changes in strategy.