Hello, I want to create an IRF for a negative innovation. I read that the standard innovation is a positive one-unit shock and I was wondering whether/ how it
is possible to change the type of the innovation to be negative? For a linear IRF, or impulse response function (which will be forthcoming from a linear VAR) the effect of (k x \sigma) is k times the effect of 1 \sigma, where k is any real number (including -1). Thus one can calculate the effect of any scaling of the standard +1 \sigma shock from the reported IRF.