Re: st: SE and CI by mrtab

[Abu Camara <abucamara@gmail.com>]

Dear Nick & sam,

I could not find such in SPSS as well.
Abu.

On 15 May 2012 00:43, Steve Samuels <sjsamuels@gmail.com> wrote:
> Each "percentage" has the form P = (mentions of category X)/(number of mentions).  Numerator and denominator are random for each person, so the percentages are actually
> ratios:
>
> ******************************
>  use http://fmwww.bc.edu/RePEc/bocode/d/drugs.dta, clear
>  mrtab inco1-inco7, include title(Sources of income) width(24)
>  egen sumi = rowtotal(inco*)
>  ratio inco1/sumi
> *****************************
>
> Since Abu is knowledgeable about SPSS, I'd appreciate a reference to the confidence interval formulas that SPSS uses when percentages add to more than 100%.  (I couldn't find one in the SPSS 16 algorithms manual.)  I'd appreciate it also if he would compare the calculation above to the one that SPSS reports.
>
> Steve
> sjsamuels@gmail.com
>
>
> On May 14, 2012, at 8:40 AM, Nick Cox wrote:
>
> If a program is counting mentions, they are not people. Either way, I stand by what I said. I don't think even "sample size" is well defined for such data, so I don't see how inference is well defined.
>
> I can't comment on what SPSS does, but I repeat my request. I would be grateful for literature references showing that SPSS, or anybody else, really has a solution for this problem. Just counting mentions regardless of where they come from sounds somewhere between dubious and fallacious to me.
>
> The author of -mrtab- is Ben Jann, who is not a member of Statalist. If you want his answers, you need to write to him directly.
>
> Nick
> n.j.cox@durham.ac.uk
>
> Abu Camara
>
> Thanks Nick. Consider the table below and you want to get the "se"
> & "ci"for the responses variable which are in percentages. I was able
> to do this for
> other survey questions which are not multiple responses. Perhaps the
> author might consider
> including standard errors & confidence interval generation in his
> program. I will have to turn to
> SPSS which has the facility.
>
> --------------------------------------------------------------------------------------------------------.
>
> mrtab inco1-inco7, include title(Sources of income) width(24)
>
> Pct. of     Pct. of
> Sources of income       Freq.   responses       cases
> -------------------------------+-----------------------------------
> inco1          private support         226       12.83       23.25
> (partner, family,
> friends)
> inco2           public support         607       34.47       62.45
> (unemployment insurance,
> social benefits)
> inco3             drug dealing         293       16.64       30.14
> inco4    housebreaking, theft,          50        2.84        5.14
> robbery
> inco5             prostitution          82        4.66        8.44
> inco6       "mischeln"/begging         151        8.57       15.53
> inco7         legal occupation         352       19.99       36.21
> -------------------------------+-----------------------------------
> Total        1761      100.00      181.17
>
>
> On 14 May 2012 14:35, Nick Cox <n.j.cox@durham.ac.uk> wrote:
>> I don't really have further comments. I was half-assuming that you know exactly what you seek, but if so you are not spelling it out.
>>
>> As I see it, you would need to specify what data generation process you expect to apply and e.g. how confidence intervals are to be defined and calculated.
>>
>> For example, if the question is mode of transport to work and the answers look like
>>
>> Car
>> Car, train, walk
>> Walk
>> Yak
>> Horse
>> Camel
>> Personal helicopter
>> ...
>>
>> it is not clear to me what meaning there could be to a standard error around the percent of people who say "walk". If the principle is that people can specify a variety of answers, the associated data generation process seems elusive to me. You can always count "mentions" rather than "people" but the inference for that I don't think is obvious.
>>
>> So, I don't think you can blame Stata for neglecting this area unless you can point to literature in which the logic is explained.
>>
>> Nick
>> n.j.cox@durham.ac.uk
>>
>> Abu Camara
>>
>> Hi Nick,
>>
>> Thanks for the reply.
>> I have no idea of writing my own program for "mrtab" to compute "se" &
>> "ci". Further help/suggestion would be appreciated.
>> Official Stata appears to be weak in complex tabulation.
>> Abu.
>>
>> On 14 May 2012 12:18, Nick Cox <njcoxstata@gmail.com> wrote:
>>> SJ-5-1  st0082  . . . . . . . . . . . . . . . Tabulation of multiple responses
>>>        (help _mrsvmat, mrgraph, mrtab if installed)  . . . . . . . .  B. Jann
>>>        Q1/05   SJ 5(1):92--122
>>>        introduces new commands for the computation of one- and
>>>        two-way tables of multiple responses
>>>
>>> You are correct, I think. -mrtab- doesn't provide these, so you may
>>> need to write your own program.
>>>
>>> Nick
>>>
>>> On Mon, May 14, 2012 at 10:09 AM, Abu Camara <abucamara@gmail.com> wrote:
>>>
>>>> I am running one and two way tables of multiple response using the
>>>> user-written command "mrtab" (Stata 11.2). I tried to generate both
>>>> standard errors and
>>>> confidence intervals for tables of percentages but I could not find
>>>> this as an option.
>
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-- 
Best Wishes,

Abu Camara

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