Re: st: RE: unexpected "ambiguous abbreviation"

[Dirk Enzmann <dirk.enzmann@uni-hamburg.de>]

Thanks a lot, your answer has been to the point and very helpful, indeed!

Dirk

> Date: Tue, 26 Feb 2008 18:43:05 -0000
> From: "Nick Cox" <n.j.cox@durham.ac.uk>
> Subject: st: RE: unexpected "ambiguous abbreviation"
>
> Scalars and variable names share the same name space. That is in the
> manual [P] 
> and discussed at length within 
> SJ-6-2  dm0019  . Stata tip 31: Scalar or variable? Problem of ambiguous
> names
>         . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  G. I.
> Kolev
>         Q2/06   SJ 6(2):279--280                                 (no
> commands)
>         tips for avoiding abbreviation conflicts with variables
>         when naming scalars
>
> What you want is 
> tempname mu 
> scalar `mu' = <whatever> 
> Similarly, it is good practice to use tempnames for all scalars within
> programs, unless you have 
> a very good reason to the contrary. 
> If you go 
> tempname mu 
> scalar mu = <whatever>
>
> then that is legal, but makes no use of the tempname. 
> If you use tempnames for all your scalars, there will be no clash
> between scalar names and 
> existing variable names, and no need to fiddle with whether variable 
> abbreviation is on or off. In any case, note that if you have a scalar
> mu 
> and a variable name mu, then there is a clash regardless of whether
> variable 
> names can be abbreviated. In fact, I don't think you should mess with
> variable 
> abbreviation in most programs. 
> Nick 
> n.j.cox@durham.ac.uk 
> Dirk Enzmann
>
> Does somebody have an idea why I receive the error message "mu ambiguous
>
> abbreviation" if the data contain variable starting with mu...? Below 
> the result of trying to run my program "fitnb" with  - set trace on - 
> and - set tracedepth 1 -.
>
> I thought that using "tempvar mu" followed by "scalar mu = something" 
> would result in mu being a temporary scalar (no macro!) existing only 
> within the call of the program fitnb.
>
> BTW, is there a possibility to check quietly the setting of varabbrev? 
> So that I could use "set varabbrev off" at the beginning of the program 
> and "set varabbrev on" at the end only if it has been "on" before (so 
> that a call to the program will never change the setting "varabbrev" 
> outside the program)? Because to use "set varabbrev off" is an effective
>
> workaround.
>
> Thanks in advance,
> Dirk
>
> =====================================================================
> fitnb rbinz99
> - ----------------------------------------------------- begin fitnb ---
> - - version 9
> - - syntax [varlist] [, maxval(integer 0)]
> - - tokenize `varlist'
> = tokenize rbinz99
> - - args x
> - - tempvar x_max size mu N prob i nbdat maxfit pmisfit
> - - if `maxval'==0 {
> = if 0==0 {
> - - local selection "if `x'<."
> = local selection "if rbinz99<."
> - - }
> - - else {
>    local selection "if `x'<. & `x'<=`maxval'"
>    }
> - - sum `x' `selection'
> = sum rbinz99 if rbinz99<.
>
>      Variable |       Obs        Mean    Std. Dev.       Min        Max
> - -------------+--------------------------------------------------------
>       rbinz99 |      9081    .2542672    2.124223          0        150
> - - scalar x_max = r(max)
> - - quietly nbreg(`x') `selection'
> = quietly nbreg(rbinz99) if rbinz99<.
> - - scalar size = 1/exp(_b[/lnalpha])
> - - scalar mu = exp(_b[_cons])
> - - scalar N = e(N)
> - - scalar prob = size/(size+mu)
> mu ambiguous abbreviation
> - ------------------------------------------------------- end fitnb ---
> r(111);
> =====================================================================

--
*************************************************
Dr. Dirk Enzmann
Institute of Criminal Sciences
Dept. of Criminology
Schlueterstr. 28
D-20146 Hamburg
Germany

phone: +49-(0)40-42838.7498 (office)
       +49-(0)40-42838.4591 (Mrs Billon)
fax:   +49-(0)40-42838.2344
email: dirk.enzmann@uni-hamburg.de
www: 
http://www2.jura.uni-hamburg.de/instkrim/kriminologie/Mitarbeiter/Enzmann/Enzmann.html
*************************************************
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