dlog(x,y,z) returns NAs

[nupogodi]

am i wrong in something??

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wfcreate(wf=test,page=sht1) m 1998m1 2012m12 %a="myseries" series {%a} = rnd+2 'this line works fine series {%a} = log({%a}) 'this line works fine series {%a} = d({%a},0,12) 'BUG! returns NAs, but should return values series {%a} = dlog({%a},0,12) 'BUG! returns NAs, but should return values

[startz]

There are two things going on here.

First, you are getting some NA's because you are asking for a difference where the lagged term starts before the data range. As an example, if you say

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dlog(x,1)

then your smpl needs to be set to begin with the second observation or later.

Second, there appears to be a bug in EView where the differencing operator equals zero. EViews acts, incorrectly, as if the argument equaled 1.

[EViews Gareth]

Startz:
d(x,0,1) is not the same as d(x,1,1).

However, you are right that d(x,0)=d(x,1) in EViews. Perhaps this is a bug, but it isn't a big one :D

[startz]

Startz:
d(x,0,1) is not the same as d(x,1,1).

Right, separate issues.

However, you are right that d(x,0)=d(x,1) in EViews. Perhaps this is a bug, but it isn't a big one :D

It's only a bug in the sense that EViews produces the wrong answer.

[EViews Gareth]

True, it is just that is it completely unrelated to the initial post/question :D

The reason the user is getting NAs is because, as you pointed out, the difference doesn't exist for the first observation, which is not a bug at all.