Re: st: variables precision

[Kyle Hood <kyle.hood@yale.edu>]

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
> > >
> > >
> > >
> > >
> > >
> > >
> > > ___________________________________
> > > L'email della prossima generazione? Puoi averla
> > con la nuova Yahoo! Mail:
> > > http://it.docs.yahoo.com/nowyoucan.html
> > > *
> > > *   For searches and help try:
> > > *
> > http://www.stata.com/support/faqs/res/findit.html
> > > *   http://www.stata.com/support/statalist/faq
> > > *   http://www.ats.ucla.edu/stat/stata/
> > *
> > *   For searches and help try:
> > *
> > http://www.stata.com/support/faqs/res/findit.html
> > *   http://www.stata.com/support/statalist/faq
> > *   http://www.ats.ucla.edu/stat/stata/
>
>
>
>
>
>
> ___________________________________
> L'email della prossima generazione? Puoi averla con la nuova Yahoo! Mail:
> http://it.docs.yahoo.com/nowyoucan.html
> *
> *   For searches and help try:
> *   http://www.stata.com/support/faqs/res/findit.html
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/