Professor Martin, thanks a lot for your quick answer,
in fact I've used stata transfer to transfer a data set from an excel
spreed sheet to a stata format,
the format of my missing values on the excel spreed sheet are #N/A.
When I've transformed them to stata, sometimes I'get the "." and
others just complet empty boxes.
perhaps the problems in on the format of the variables, when I'm
getting the "." the format is byte but the problem appears when the
format is string
any hints?
thanks a lot in advance.
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