topic Re: Use polynomial regression result to predict future in QlikView

Use polynomial regression result to predict future

Fri, 20 Jul 2012 16:42:33 GMT

I have a follow up question about the polynomial regression. How to use the regression result to forcast future?

I mentioned there is statistical function for linear regression: linest_m and linest_b, so we can use linest_m and linest_b to forcast future.

But i don't know whether there is representation of a1, a2, a3, a4, m in the formula below

Y = a1 * x^4 + a2 * x^3 + a3 * x^2 + a4 * x + m

Thanks!

Re: Use polynomial regression result to predict future

Mon, 23 Jul 2012 17:19:50 GMT

Does anyone know whether this is feasible?

Thanks!

Re: Use polynomial regression result to predict future

nagaiank — Mon, 23 Jul 2012 18:06:48 GMT

I think this is possible.

Try the 'axes' tab of the chart properties window.

Check the 'forecast' checkbox and

in the box below, enter the number of x-axis values you want to forecast.

Re: Use polynomial regression result to predict future

Mon, 23 Jul 2012 18:14:44 GMT

Thanks a lot!

It there a way that can show the forcast number? The feature you mentioned is really cool, but it does not show the forcast numbers.

Re: Use polynomial regression result to predict future

nagaiank — Mon, 23 Jul 2012 19:05:36 GMT

I think that by using linest_m() and linest_b() you may be able to forecast.

I am not sure how you can use polynomial regression for calculating forecast. But as Qlikview proposes a1, a2, a3, a4, values in the form of equation, you may see if you are able to capture these coefficients using a macro and then use them for forecasting.