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Hi, could you clarify why negative values and zeros are not allowed for the multiplicative holt-winters exponential smoothing? I tried to read over the documentation, but couldn't find the explanation for that. I used the same methodology in Statistica and it worked with negative values and zeros in...

How is pch calculated in Eviews? is it [x(t)-x(t-1)]/x(t-1)?

What would happen if we are at boundary conditions, such as x(t-1) is negative, or both x(t) and x(t-1) are negative?

Thank you in advance.