Re: st: backward incompatibility of -normden- for -normalden-

[Nick Cox <njcoxstata@gmail.com>]

-normden()- is a function, not a command. (Whatever the terminology
elsewhere, in Stata commands and functions are not synonyms, and do
not overlap.)

As you say, it's the old name, and that's documented. See

http://www.stata.com/help.cgi?normden()

or the corresponding help entry.  (Specifying "()" on function names
is a good detail in looking for -help-.)

As you say, in recent Statas, it works only under -version- control.

Nick

On Thu, Jan 10, 2013 at 12:46 AM, annoporci <annoporci@gmail.com> wrote:

> I have discovered that the old form of -normalden- named -normden- is
> somewhat deprecated.
>
> In a Statalist exchange dating back to 2004, Vince Wiggins of StataCorp
> showed how to superimpose vertical density line plots for the distribution
> of the disturbances on a regression line. I thought it was very nice and
> wanted to reproduce it.
>
> http://www.stata.com/statalist/archive/2004-07/msg00476.html
>
> But it didn't work as written. The code stopped working from Stata 10
> (i.e. if I copy the code as written in the cited url, it will work with
> the "version 9" statement added before it but not otherwise).
>
> The problem is caused by the old command -normden-
>
> By replacing -normden- by -normalden- the code works in Stata 10,11,12.
>
> As can be seen from the code I copy below, it is only inside the -range()-
> expression that the problem with old form exists, elsewhere -normden-
> still works.
>
> I'm posting this for the record because it took me a while to understand
> what the problem was.
>
> The error message had some clues:
>
> unknown function normden()
> option range() requires two numbers
>
> but as I was under the impression that -normden- was a short form of
> -normalden- (like -gen- is a short form of -generate-), I assumed the
> problem must be with the quotes around the arguments of -range-. When I
> googled for -normden- I was directed to a lot of code that uses it, so I
> did not suspect that the problem could be there. And when I cut off the
> range() from the code, it worked despite the presence of other instances
> of -normden- I therefore spent some time testing whether the quotes had
> problems.
>
> It's only after being directed to a passage in Nick Cox's article, that
> the meaning of "unknown function normden()" hit me. Nick writes: "In Stata
> 9, normalden() is the name for the function previously called normden()".
>
> There is no mention of the old name -normden- on the Stata help page for
> -normalden-.
>
> --
> Patrick Toche.
>
> A1  - Cox, N. J.
> TI  - Speaking Stata: Density probability plots
> JF  - Stata Journal
> PB  - Stata Press
> CY  - College Station, TX
> Y1  - 2005
> UR  - http://www.stata-journal.com/article.html?article=gr0012
>
>
>
> clear all
> sysuse auto
> keep if foreign
> sort weight
>
> gen weight2 = weight^2
> regress mpg weight weight2
> predict fit
> predict se, stdp
>
> /// original code by Vince Wiggins
> /// http://www.stata.com/statalist/archive/2004-07/msg00476.html
>
> #delimit ;
> twoway sc mpg weight , pstyle(p3) ms(o)
>         ||
>                 fn weight[3]  - 1000 * normden(x, `=fit[3]' , `=se[3]')
>                 , range(`=fit[3]-5' `=fit[3]+5') horiz pstyle(p1)
>         ||
>                 fn `=fit[3]' , range(`=weight[3]'
> `=weight[3]-1000*normalden(0,0,
> se[3])') pstyle(p1)
>         ||
>                 fn weight[17] - 1000 * normden(x, `=fit[17]', `=se[17]')
>                 , range(`=fit[17]-5' `=fit[17]+5') horiz pstyle(p1)
>         ||
>                 fn `=fit[17]', range(`=weight[17]'
> `=weight[17]-1000*normalden(0,0,
> se[17])') pstyle(p1)
>         ||
>                 fn weight[21] - 1000 * normden(x, `=fit[21]' , `=se[21]')
>                 , range(`=fit[21]-7' `=fit[21]+7') horiz pstyle(p1)
>         ||
>                 fn `=fit[21]', range(`=weight[21]'
> `=weight[21]-1000*normalden(0,0,
> se[21])') pstyle(p1)
>         ||
>                 line fit weight
>         , clwidth(*2)
>         legend(off)
>         ytitle("Miles per gallon")
>         xtitle("Weight")
>         title("Scatter with Regression Line and Confidence Interval
> Densities",
> size(4.8) margin(t=0 b=1.5) span)
> ; #delimit cr
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