Hi again,

My question is not directly related to R, but I still hope to get some
quality feedback on my question.

In a typical time series analysis, we generally take logarithm of the
underlying variable and then fit models like ARIMA etc on that transformed
variable. This has a related benefit to getting linear trend for model
variable instead of quadratic

This essentially assumes that, the variable under study is strictly
positive. However what if my variable is mix of positive, zero, and
negative? would it then make sense to fit model on the raw variable without
transforming it anyway?

Is anybody aware of any standard policy to handle such situation?

Thanks for your input.

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