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AW: st: AW: RE: AW: Identifying unique values with codebook


From   "Martin Weiss" <[email protected]>
To   <[email protected]>
Subject   AW: st: AW: RE: AW: Identifying unique values with codebook
Date   Wed, 16 Jun 2010 16:56:17 +0200

<> 
"
>From the help:
 " The inspect command provides a quick summary of a numeric variable""




If this is its purpose, why not reject non-numeric data out of hand, then?
Instead -inspect- declares strings to be all missing. Worse still, the upper
part of its output says 

"unique values:  2"


while under its histogram, it claims 

"(0 unique value)"




HTH
Martin


-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Steve Samuels
Gesendet: Mittwoch, 16. Juni 2010 16:32
An: [email protected]
Betreff: Re: st: AW: RE: AW: Identifying unique values with codebook

>From the help:
 " The inspect command provides a quick summary of a numeric variable"
As -sum- reports 0 values for a string variable, so does -inspect-.

Steve

-
Steven Samuels
[email protected]
18 Cantine's Island
Saugerties NY 12477
USA
Voice: 845-246-0774
Fax:    206-202-4783


On Wed, Jun 16, 2010 at 10:24 AM, Martin Weiss <[email protected]> wrote:
>
> <>
>
> A "string representation" seems to work with -codebook-, but not -inspect-
> which claims to find o unique values...
>
>
> *************
> clear*
> inp str25 mystrvar
> loooooooooooooooooooooooooooonnggg
> verylooooooooooooooooooooonnnnnnnnngggg
> end
> ins
> codebook
> *************
>
>
>
> HTH
> Martin
>
>
> -----Ursprüngliche Nachricht-----
> Von: [email protected]
> [mailto:[email protected]] Im Auftrag von Nick Cox
> Gesendet: Mittwoch, 16. Juni 2010 16:13
> An: [email protected]
> Betreff: st: RE: AW: Identifying unique values with codebook
>
> As Martin says, at root this is a precision problem.
>
> Neither -codebook- nor anything else is to blame if it is presented with
> the same values. To hold very large integers you may need to consider
> -long- as another possibility, or even a string representation.
>
> Nick
> [email protected]
>
> Martin Weiss
>
> As -help data_types- says: "doubles have 16 digits of accuracy." So you
> can
> increase the digits of your "y" up to the point where even -double- can
> do
> nothing for you:
>
> *************
> clear
> set obs 10
> gen byte x=_n
> codebook x
> gen double y1 = 1000000000000000 + x
> gen double y2 = 10000000000000000 + x
> gen double y3 = 100000000000000000 + x
> gen double y4 = 1000000000000000000 + x
> codebook y?
> ins y?
> *************
>
>
> Interestingly, -inspect- seems to differ from -codebook-`s opinion.
>
> Walter Garcia-Fontes
>
> I stumped into a problem when identifying unique values of a numeric
> variable using "codebook": if the values are large they will be
> identified as the same value.
>
> For instance I have a variable x with the following values:
> 0, 1, 2, ... 10 (that is 10 different values)
>
> codebook x
> reports "unique values: 10"
>
> Now do
> gen y = 100000000000000000 + x
>
> codebook y
> reports "unique values = 1"
>
> Is this a feature?
>
> *
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