# Re: st: variables precision

 From sara borelli To statalist@hsphsun2.harvard.edu Subject Re: st: variables precision Date Thu, 5 Apr 2007 03:03:04 +0200 (CEST)

```thank you very much!!

--- Kyle Hood <kyle.hood@yale.edu> ha scritto:

> Another possibility would be to generate a variable
> that is the
> difference between the two variables,
>
> gen z = y - x
>
> and count if z is small, e.g.,
>
> count if z > 0.0000001
>
> This won't be perfect, but as long as the variables
> are generated at
> random, there's only a tiny chance that they'll fall
> within such a small
> bound randomly.
>
> Kyle
>
>
> On Thu, 5 Apr 2007, sara borelli wrote:
>
> > I tried but after converting to float stata still
> > reports that for some observations the inequality
> is
> > satisfied , and I do not understand why...
> >
> > --- Kyle Hood <kyle.hood@yale.edu> ha scritto:
> >
> >> couldn't you just recast both as floats
> (generating
> >> a new pair of
> >> variables), do the operation, and then, if you
> wish,
> >> delete the new
> >> variables?
> >>
> >> something like this
> >>
> >> gen float xf = x
> >> gen float yf = y
> >> gen z = xf < yf
> >> drop xf yf
> >>
> >>
> >>
> >> On Thu, 5 Apr 2007, sara borelli wrote:
> >>
> >>> Dear Statalist members
> >>>
> >>> I know this is a precision question already
> posted
> >> in
> >>> the past, but I have difficulties to understand
> >> the
> >>> right way to go even after looking at the
> archives
> >> of
> >>> statalist
> >>>
> >>> I have two variables:
> >>>  x        y
> >>> 17.68    17.68
> >>> 15.56    15.56
> >>> 19.27    19.27
> >>> 5.3      5.3
> >>>
> >>> If I write 'count if x<y' stata says that all
> >>> observations satisfy this inequality, when in
> fact
> >> the
> >>> values 'look' the same. I think this has to do
> >>> with the fact that x is stored as double, while
> y
> >> is
> >>> stored as float. Is there any way I can say
> stata
> >> to
> >>> read the values as they "appear" and thus
> >> performing
> >>> calculations correctly (in this case I would
> need
> >>> stata say that there are zero observations for
> >> which
> >>> x<y)? I am sorry to repeat this question, but
> any
> >>> suggestion would be really appreciated
> >>>
> >>> thanks
> >>> Sara
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> ___________________________________
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> >
> >
> >
> >
> >
> >
> >
> > ___________________________________
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```