Thk u so much mr john for your explanation.
I want to know why the total avaerge must add up to 400 and 0 using the multiplicative and additive model respectively?

With the multiplicative method, the variations are all bit more or a bit less than a 100. On average they are 100 and if there are 4 of them then the total must be 400.

With the additive model that are all a bit more than zero or a bit less than zero, so the average is zero and the total should be zero.

you said in the video that to check that the centered averages are reasonably linear, we can put them on a graph and see if they are more or less liner but I want to ask could we not use correlation coefficient to check the linearity?

Hi sir! In the video you said to use regression analysis to forecast trend. But could you please tell how? What will we take as variable x and what will we take as variable y?

Pameh says

Thk u so much mr john for your explanation.

I want to know why the total avaerge must add up to 400 and 0 using the multiplicative and additive model respectively?

John Moffat says

With the multiplicative method, the variations are all bit more or a bit less than a 100. On average they are 100 and if there are 4 of them then the total must be 400.

With the additive model that are all a bit more than zero or a bit less than zero, so the average is zero and the total should be zero.

Pameh says

Thank you so much for your clear response

John Moffat says

You are welcome 🙂

mannannagpal says

you said in the video that to check that the centered averages are reasonably linear, we can put them on a graph and see if they are more or less liner but I want to ask could we not use correlation coefficient to check the linearity?

John Moffat says

Yes – by all means.

mannannagpal says

Hi sir! In the video you said to use regression analysis to forecast trend. But could you please tell how? What will we take as variable x and what will we take as variable y?