Re: st: loop: integrate generate syntax in existing loop

[Nick Bornschein <nick.bornschein@googlemail.com>]

Hello Nick,

thank you so much. that helped a lot.

Best
-Nick


Am 04.07.13 12:46, schrieb Nick Cox:
> Lots of problems here. The immediate problem is that this is one loop
> only, not multiple nested loops. So, this should work so far as Stata
> is concerned.
>
> foreach x of varlist a-d {
>           ttest `x', by(group)
>           gen lower_`x' = r(mu_1) - r(sd_1)*1.96
>           gen upper_`x' = r(mu_1) + r(sd_1)*1.96
>           gen lower2_`x' = r(mu_2) - r(sd_2)*1.96
>           gen upper2_`x' = r(mu_2) + r(sd_2)*1.96
> }
>
> That said, what are you trying to do here?  Mean +/- 1.96 SD looks
> like an attempt to get a 95% confidence interval for each mean but the
> multiplier of 1.96 would be better as a t-based multiplier (small
> problem) and the SD is not the same as the standard error of the mean
> (big problem). Better to use -ci- on each group, something like this.
>
> foreach x of varlist a-d {
>           ci  `x' if group == 1
>           gen `x'_upper_1  = r(ub)
>           gen `x'_lower_1  = r(lb)
>           ci  `x' if group == 2
>           gen `x'_upper_2  = r(ub)
>           gen `x'_lower_2  = r(lb)
> }
>
> Naturally your values for -group- may not be 1 and 2.
>
> All that said, the strategy of using -generate- to put several single
> constants in new variables may not be ideal for what you really want
> downstream, but I will stop there.
>
> Nick
> njcoxstata@gmail.com
>
>
> On 4 July 2013 11:27, Nick Bornschein <nick.bornschein@googlemail.com> wrote:
> > Hi,
> >
> > I want to include multiple generate commands in a ttest loop (which is
> > working perfect without the generate), but I don't get it...
> >
> > foreach x of varlist a-d {
> > ttest `x', by(group)    {
> > gen lower_`x' = r(mu_1) - r(sd_1)*1.96    {
> > gen upper_`x' = r(mu_1) + r(sd_1)*1.96    {
> > gen lower2_`x' = r(mu_2) - r(sd_2)*1.96    {
> > gen upper2_`x' = r(mu_2) + r(sd_2)*1.96    {
> >      }
> >      }
> >      }
> >      }
> >      }
> > }
> >
> > How to integrate the generate?
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/faqs/resources/statalist-faq/
> *   http://www.ats.ucla.edu/stat/stata/

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/