Re: st: Advice on content of a do file

[Stas Kolenikov <skolenik@gmail.com>]

Sergiy,

both the original solution and your solution are hacks exploiting
rather sophisticated Stata functionality and strong coupling. If for
whatever incompatibility reason it breaks down, the end user is left
to guess what's going on. They still make a lot of assumptions about
the user of the code and their data. A responsible developer would
provide robust code that might:

* check that stability variable exists, and is of the right type
capture confirm numeric variable stability
if _rc {
  display as err "Variable stability is not found, or is of wrong type"
  exit 7
}
* check that it has the right range
assert inlist(stability,1,2,3,4) if !missing(stability)
if _rc {
  display as err "The values of stability are expected to range from 1 to 4"
  exit 7
}
* and assign the new values to that variable, whatever solution is
used for that.

See also "How to be assertive" at
http://www.stata-journal.com/sjpdf.html?articlenum=dm0003.


-- Stas Kolenikov, PhD, PStat (ASA, SSC)
-- Senior Survey Statistician, Abt SRBI
-- Opinions stated in this email are mine only, and do not reflect the
position of my employer
-- http://stas.kolenikov.name



On Fri, Jul 26, 2013 at 10:28 AM, Sergiy Radyakin
<serjradyakin@gmail.com> wrote:
> the code works just fine, as in the following example:
> sysuse auto,clear
> matrix UTILS=(-0.001,0.101,0.191,0.222\/*
>> */-0.024,0.096,0.189,0.228\/*
>> */0.006, 0.084, 0.156, 0.188\/*
>> */0.021, 0.091, 0.159, 0.181\ /*
>> */ -0.003, 0.069, 0.154, 0.181)
>
> gen stability=_n
> gen sta_index=UTILS[1,stability[_n]]
>
> However it relies on stability being a numeric variable. The error
> message 509 is consistent with stability being a string variable. You
> may want to investigate why this happened, and if it can be
> -destring-'ed or otherwise converted to numeric codes.
>
> Note, that Stas is right that there are other ways to write the same.
> I would prefer here:
>
> generate sta_index = real(word("-0.001 0.101 0.191 0.222",stability))
>
> Best, Sergiy
>
>
> On Fri, Jul 26, 2013 at 11:16 AM, Stas Kolenikov <skolenik@gmail.com> wrote:
>> This is a TERRIBLE way to write code. It relies too heavily on having
>> things specified exactly as the developer thought, rather than
>> adapting to the users' data. Instead, it should have been written as
>>
>> gen sta_index = .
>> replace sta_index = -0.001 if stability == 1
>> replace sta_index = 0.101 if stability == 2
>> replace sta_index = 0.191 if stability == 3
>> replace sta_index = 0.222 if stability == 4
>>
>> etc.
>>
>> It looks like the developers thought their code would work, but never
>> tried it. And it did not, in practice.
>>
>>
>> -- Stas Kolenikov, PhD, PStat (ASA, SSC)
>> -- Senior Survey Statistician, Abt SRBI
>> -- Opinions stated in this email are mine only, and do not reflect the
>> position of my employer
>> -- http://stas.kolenikov.name
>>
>>
>>
>> On Fri, Jul 26, 2013 at 1:12 AM, Peter King <kingsocres@gmail.com> wrote:
>>> Hi All,
>>>
>>> I'm preparing to analyse survey responses to the ICECAP-A questionnaire. The
>>> ICECAP-A developers have provided code to substitute into a Stata do file to
>>> allow the calculation of values or tariffs for each respondent.
>>>
>>> The code is as follows:
>>>
>>> matrix UTILS=(-0.001,0.101,0.191,0.222\/*
>>>
>>> */-0.024,0.096,0.189,0.228\/*
>>>
>>> */0.006, 0.084, 0.156, 0.188\/*
>>>
>>> */0.021, 0.091, 0.159, 0.181\ /*
>>>
>>> */ -0.003, 0.069, 0.154, 0.181)
>>>
>>> gen sta_index=UTILS[1,stability[_n]]
>>>
>>> gen att_index=UTILS[2,attachment[_n]]
>>>
>>> gen aut_index=UTILS[3,autonomy[_n]]
>>>
>>> gen ach_index=UTILS[4,achievement[_n]]
>>>
>>> gen enj_index=UTILS[5,enjoyment[_n]]
>>>
>>> gen tariff=sta_index+att_index+aut_index+ach_index+enj_index
>>>
>>>
>>> I have formatted my data as specified below:
>>>
>>> "This code, when substituted into a Stata do file, will allow calculation of
>>> ICECAP-A tariffs for each respondent in a study, based on their answers to
>>> the five classification questions. Statistical analyses can then be
>>> conducted on these tariffs. Indeed they can be conducted on the five index
>>> values also, to ascertain sensitivity of these to differences in factors.
>>>
>>>
>>> "Data should be set up with one study participant per row. As specified on
>>> the ICECAP-A questionnaire, coding should be such that the 'top' level (full
>>> capability for an attribute) should take the value '4', down to the bottom
>>> level (no capability) which should take the value '1'. NB this coding is the
>>> opposite of that used in instruments such as the EQ-5D (where 1 is top
>>> level). The five variables, containing a respondent's five ICECAP-A
>>> responses should be named stability, attachment, autonomy, achievement,
>>> enjoyment."
>>>
>>> When I run the do file with the specified content I get the following
>>> reply/output:
>>>
>>> . do "C:\Documents and Settings\User\My Documents\FCSPRU Files\Current
>>> projects\BIS 2006\Surve
>>>> ys\Postal survey\Wave 2 2012\ICECAP Tariff.do"
>>>
>>> . matrix UTILS=(-0.001,0.101,0.191,0.222\/*
>>>> */-0.024,0.096,0.189,0.228\/*
>>>> */0.006, 0.084, 0.156, 0.188\/*
>>>> */0.021, 0.091, 0.159, 0.181\ /*
>>>> */ -0.003, 0.069, 0.154, 0.181)
>>>
>>> . gen sta_index=UTILS[1,stability[_n]]
>>> matrix operators that return matrices not allowed in this context
>>> r(509);
>>>
>>> end of do-file
>>>
>>> r(509);
>>>
>>> .
>>> I am new to using do files and wonder whether I should be including other
>>> information in the do file?  Or is something else wrong in the code?
>>>
>>> Any suggestions from more experienced users will be greatlt appreciated.
>>>
>>>
>>> Many thanks,
>>>
>>> Peter King
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