dear users,
when I drop some observations by writing:
1) drop if x>123
Stata drops also the missing values of the x variable. When I use the
following
2) drop if x>123 & x!=.
Stata does not drop the missing values
As missing values are discarded in any estimations, Stata should consider
the same obsevations whather command I use (1 or 2). By constrast, the
number of obsevations is much smaller when I run a regression after using
the command 1)
thank you
Francesco
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