Re: [Gretl-devel] bug with missings, dummies (and panel?)
On Tue, 13 Apr 2010, Sven Schreiber wrote:
I discovered what's IMHO a relative severe bug (severe because it
can go
unnoticed and would lead to rubbish afterwards):
Missing values are not propagated when multiplying dummy variables. Example:
open greene14_1
series check1 = (Q>100)
series check2 = zeromiss(LF <0.5)
series checkmult = check1*check2
and 'checkmult' should have missings where check2 has them but it doesn't.
That behavior is by design and IMO it's not a bug, since zero
times any value is zero. (This is the one exception we make to the
rule that NAs always propagate to the result, and it's explained
in section 5.7 of the User's Guide, "Handling missing values".)
To get the behavior you were expecting:
checkmult = !ok(check2) ? NA : check1*check2
Allin