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Re: st: example about choice experiment datasheet
From
elisabetta capobianco <[email protected]>
To
[email protected]
Subject
Re: st: example about choice experiment datasheet
Date
Tue, 4 Dec 2012 13:12:08 +0100
Dear Arne,
the main concern about the conditional logit model is its assumption
of independence from
irrelevant alternatives (IIA). This assumption implies that the
probability ratio of individuals
choosing between two alternatives does not depend on the availability
or attributes of the other
alternatives.
I have 4 alternatives for each choice set, so it's important to me to
surmount the IIA, and it's better using mixlogit than asclogit, isn't
it?
Thank you,
elisabetta
2012/11/27 Arne Risa Hole <[email protected]>:
> You are welcome. -mixlogit- implements the same model as -asclogit-
> but with random coefficients. You should make sure that you understand
> the differences between the models before moving on to -mixlogit-, as
> this is a more complicated model.
>
> Arne
>
> On 27 November 2012 05:31, elisabetta capobianco
> <[email protected]> wrote:
>> Dear Arne,
>> you're my very helpful, thank you so much.
>> Now i'm trying to use mix logit, I've ridden your article. It seems to
>> be better than asclogit, because i have different alternatives on N
>> choices occasion. Is it more correct for my case, isn't it?
>>
>> Thank you!
>>
>> elisabetta
>>
>> 2012/11/26 Arne Risa Hole <[email protected]>:
>>> This is to be expected; if you found it surprising you need to read
>>> the -asclogit- manual entry more carefully. Whether it's correct or
>>> not really depends on what you are trying to do. I would suggest that
>>> including socio-demographics in your model only makes sense if you
>>> interact them with the alternative-specific attributes, since your
>>> alternatives are unlabelled.
>>>
>>> Arne
>>>
>>> On 26 November 2012 10:43, elisabetta capobianco
>>> <[email protected]> wrote:
>>>> Ok Arne,
>>>> now It's clear and I have had good results.
>>>> Just a doubt. When I put inside the socio-demographic variables, the
>>>> output has the four alternatives 1,2,3,4, even if I write nocons.
>>>> I don't understand the meaning of this output considering that I have
>>>> unlabelled alternatives.
>>>> Is however correct this result?
>>>>
>>>> Thank you,
>>>> Elisabetta
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> 2012/11/24 Arne Risa Hole <[email protected]>:
>>>>> Elisabetta,
>>>>>
>>>>> The "case" variable must a unique identifier for each choice. You can
>>>>> generate it like this
>>>>>
>>>>> egen caseid = group(id scenario)
>>>>>
>>>>> The "alt" variable should be coded 1,2,3,4,1,2,3,4 etc. (not
>>>>> 1,2,3,4,5,6,7,8,...).
>>>>>
>>>>> Arne
>>>>>
>>>>> On 24 November 2012 16:04, elisabetta capobianco
>>>>> <[email protected]> wrote:
>>>>>> Thank you Arne, I have taken the book.
>>>>>> My problem is that I have 16 scenarios for id (n=131) with 4 different
>>>>>> alternatives for each scenario .
>>>>>> So in the dataset I have written for each id non 4 alternatives
>>>>>> (1,2,3,4) but 64 alternatives. Is it correct?
>>>>>>
>>>>>>
>>>>>>
>>>>>> id scenario alt
>>>>>> 1 1 1
>>>>>> 1 1 2
>>>>>> 1 1 3
>>>>>> 1 1 4
>>>>>> 1 2 5(or1?)
>>>>>> 1 2 6(or2?)
>>>>>> 1 2 7(or3?)
>>>>>> 1 2 8 (or4?)
>>>>>> 1 3 9(or1?)
>>>>>> .
>>>>>> .
>>>>>> .
>>>>>> .
>>>>>> .
>>>>>> 1 16 64
>>>>>> 2 1 1
>>>>>> .
>>>>>> .
>>>>>> And when I wrote:
>>>>>> asclogit choice organic price, case(id) alternatives(car) noconst
>>>>>>
>>>>>> case is id or scenario? I suppose scenario. But if is scenario I don't
>>>>>> know how to use id!
>>>>>> And alternatives are the 64 alternatives?
>>>>>>
>>>>>>
>>>>>> Thank you so much for your help.
>>>>>>
>>>>>> elisabetta
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> 2012/11/23 Arne Risa Hole <[email protected]>:
>>>>>>> Elisabetta
>>>>>>>
>>>>>>> I am fairly sure that you can use -asclogit- to do what you want. If
>>>>>>> you don't want alternative-specific constants you can use the
>>>>>>> -noconst- option. Modifying the example in the help-file slightly:
>>>>>>>
>>>>>>> webuse choice
>>>>>>> asclogit choice dealer, case(id) alternatives(car) noconst
>>>>>>>
>>>>>>> As you can see the only coefficient which is estimated in this case is
>>>>>>> the one for the dealer attribute, which is analogous to the organic
>>>>>>> and price attributes in your experiment. In your case the variable
>>>>>>> that identifies the alternatives for each case ("car" in the example)
>>>>>>> can simply take the values 1, 2, 3 and 4 since your alternatives are
>>>>>>> unlabelled.
>>>>>>>
>>>>>>> I also recommend taking a look at a basic choice modelling text before
>>>>>>> proceeding, such as
>>>>>>> http://books.google.co.uk/books/about/Applied_Choice_Analysis.html?id=8yZrtCCABAgC.
>>>>>>>
>>>>>>> Good luck!
>>>>>>>
>>>>>>> Arne
>>>>>>>
>>>>>>> On 23 November 2012 13:25, elisabetta capobianco
>>>>>>> <[email protected]> wrote:
>>>>>>>> I think that asclogit is not the right comand for me.
>>>>>>>> Because I have 4 unlabeled alternatives, 16 diferrent scenarios with 4
>>>>>>>> alternatives for 131 individuals. So my indipendent viariables are the
>>>>>>>> attributes and dipendent variables the utility for each level of
>>>>>>>> attribute.
>>>>>>>> I need to know the importance of every level, not of alternatives.
>>>>>>>> Ex.:n=131
>>>>>>>> scenario 1) A B C D
>>>>>>>> organic org no org no org org
>>>>>>>> price 4 8 4 4
>>>>>>>> scenario 2) A B C D
>>>>>>>> organic no org no org org no org
>>>>>>>> price 12 16 8 8
>>>>>>>> .
>>>>>>>> .
>>>>>>>> .
>>>>>>>> Perhaps with mixlogit? Because the example is on a specific
>>>>>>>> alternative, car or bus.
>>>>>>>> I instead need to know the coefficient of attributes and levels.
>>>>>>>>
>>>>>>>> I don't know if I have explained well, I hope!
>>>>>>>>
>>>>>>>> e
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> 2012/11/23 Arne Risa Hole <[email protected]>:
>>>>>>>>> -help asclogit_postestimation-
>>>>>>>>>
>>>>>>>>> Arne
>>>>>>>>>
>>>>>>>>> On 23 November 2012 11:05, elisabetta capobianco
>>>>>>>>> <[email protected]> wrote:
>>>>>>>>>> Dear Arne,
>>>>>>>>>> i need to estimate the marginal effect of levels on attributes of my choice.
>>>>>>>>>> Is it possible?
>>>>>>>>>> es:
>>>>>>>>>> about meat:
>>>>>>>>>> attribute level
>>>>>>>>>> label organic/not organic
>>>>>>>>>> origin local abroad
>>>>>>>>>> prize 4/8
>>>>>>>>>>
>>>>>>>>>> I would know the utility for each level of each attribute.
>>>>>>>>>>
>>>>>>>>>> Thank you!
>>>>>>>>>> elisabetta
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> 2012/11/21 elisabetta capobianco <[email protected]>:
>>>>>>>>>>> Thank you so much Arne!!!
>>>>>>>>>>> I'm creating the data set and then i'll try to run in Stata!
>>>>>>>>>>>
>>>>>>>>>>> Elisabetta
>>>>>>>>>>>
>>>>>>>>>>> 2012/11/20 Arne Risa Hole <[email protected]>:
>>>>>>>>>>>> Elisabetta
>>>>>>>>>>>>
>>>>>>>>>>>> -mlogit- is not very useful to model data from choice experiments as
>>>>>>>>>>>> it does not allow alternative-specific explanatory variables.
>>>>>>>>>>>> -asclogit- requires your data to be in long form (one row per
>>>>>>>>>>>> alternative); see -help asclogit- and the first example in the paper I
>>>>>>>>>>>> mentioned in my last email.
>>>>>>>>>>>>
>>>>>>>>>>>> Arne
>>>>>>>>>>>>
>>>>>>>>>>>> On 20 November 2012 10:04, elisabetta capobianco
>>>>>>>>>>>> <[email protected]> wrote:
>>>>>>>>>>>>> Thank you Arne, I want to use asclogit and mlogit for my choice modelling.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> 2012/11/19 Arne Risa Hole <[email protected]>:
>>>>>>>>>>>>>> Elisabetta
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> As Jay says the correct data form depends on the estimation command
>>>>>>>>>>>>>> you are planning to use, so this is a very important piece of
>>>>>>>>>>>>>> information that you haven't given us. You may find the examples in
>>>>>>>>>>>>>> http://www.stata-journal.com/article.html?article=st0133 useful.
>>>>>>>>>>>>>> Generally speaking the best strategy is to import the data into Stata
>>>>>>>>>>>>>> and then use commands like -reshape- to convert the data into the form
>>>>>>>>>>>>>> you want, rather than trying to do this in Excel.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Arne
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On 19 November 2012 15:51, elisabetta capobianco
>>>>>>>>>>>>>>> <[email protected]> wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Thank you for your answer!
>>>>>>>>>>>>>>>> I want to do a mixed logit, but I have found a data set on help file
>>>>>>>>>>>>>>>> with just one choice set. I have 16 choice sets and I don't know how
>>>>>>>>>>>>>>>> to fil the excel data set.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> 2012/11/18 JVerkuilen (Gmail) <[email protected]>:
>>>>>>>>>>>>>>>> > On Sun, Nov 18, 2012 at 4:11 AM, elisabetta capobianco
>>>>>>>>>>>>>>>> > <[email protected]> wrote:
>>>>>>>>>>>>>>>> >> Hi, I'm new of statalist and stata!
>>>>>>>>>>>>>>>> >> I'm working on choice experiment about food preferences in schools.
>>>>>>>>>>>>>>>> >> I have 4 alternatives unlabelled, 4 attributes and 4 levels, 130
>>>>>>>>>>>>>>>> >> individuals.
>>>>>>>>>>>>>>>> >> I have the data base in excel, but before insheet the file in stata
>>>>>>>>>>>>>>>> >> i'm not sure that i have put the data in the right mode in the excel
>>>>>>>>>>>>>>>> >> file.
>>>>>>>>>>>>>>>> >> Have you got an example on a excel datasheet about choice modelling?
>>>>>>>>>>>>>>>> >> Just an example to understand how to organize my datasheet.
>>>>>>>>>>>>>>>> >
>>>>>>>>>>>>>>>> > It depends on what analysis you want to use. -clogit- and procedures
>>>>>>>>>>>>>>>> > like it that are using alternative-specific predictors use the same
>>>>>>>>>>>>>>>> > basic format, which is specified in the help file. You can see the
>>>>>>>>>>>>>>>> > example dataset there. Essentially it is a "long" format like
>>>>>>>>>>>>>>>> > person-period in a growth model with time-varying covariates.
>>>>>>>>>>>>>>>> > *
>>>>>>>>>>>>>>>> > * For searches and help try:
>>>>>>>>>>>>>>>> > * http://www.stata.com/help.cgi?search
>>>>>>>>>>>>>>>> > * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>>>>>>>>>> > * http://www.ats.ucla.edu/stat/stata/
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Le informazioni contenute in questa comunicazione e gli
>>>>>>>>>>>>>>>> eventuali documenti allegati
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> hanno carattere confidenziale e sono a uso esclusivo del
>>>>>>>>>>>>>>>> destinatario. Nel caso
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>>>>>>>>>>>>>>>> che la sua diffusione
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> e riproduzione è contraria alla legge e prego di darmi
>>>>>>>>>>>>>>>> prontamente avviso
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> e di cancellare quanto ricevuto. Grazie.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> *
>>>>>>>>>>>>>>>> * For searches and help try:
>>>>>>>>>>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>>>>>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>>>>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> *
>>>>>>>>>>>>>> * For searches and help try:
>>>>>>>>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>>>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> --
>>>>>>>>>>>>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Le informazioni contenute in questa comunicazione e gli
>>>>>>>>>>>>> eventuali documenti allegati
>>>>>>>>>>>>>
>>>>>>>>>>>>> hanno carattere confidenziale e sono a uso esclusivo del
>>>>>>>>>>>>> destinatario. Nel caso
>>>>>>>>>>>>>
>>>>>>>>>>>>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>>>>>>>>>>>>> che la sua diffusione
>>>>>>>>>>>>>
>>>>>>>>>>>>> e riproduzione è contraria alla legge e prego di darmi
>>>>>>>>>>>>> prontamente avviso
>>>>>>>>>>>>>
>>>>>>>>>>>>> e di cancellare quanto ricevuto. Grazie.
>>>>>>>>>>>>>
>>>>>>>>>>>>> *
>>>>>>>>>>>>> * For searches and help try:
>>>>>>>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>>>>>>>
>>>>>>>>>>>> *
>>>>>>>>>>>> * For searches and help try:
>>>>>>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Le informazioni contenute in questa comunicazione e gli
>>>>>>>>>>> eventuali documenti allegati
>>>>>>>>>>>
>>>>>>>>>>> hanno carattere confidenziale e sono a uso esclusivo del
>>>>>>>>>>> destinatario. Nel caso
>>>>>>>>>>>
>>>>>>>>>>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>>>>>>>>>>> che la sua diffusione
>>>>>>>>>>>
>>>>>>>>>>> e riproduzione è contraria alla legge e prego di darmi
>>>>>>>>>>> prontamente avviso
>>>>>>>>>>>
>>>>>>>>>>> e di cancellare quanto ricevuto. Grazie.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Le informazioni contenute in questa comunicazione e gli
>>>>>>>>>> eventuali documenti allegati
>>>>>>>>>>
>>>>>>>>>> hanno carattere confidenziale e sono a uso esclusivo del
>>>>>>>>>> destinatario. Nel caso
>>>>>>>>>>
>>>>>>>>>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>>>>>>>>>> che la sua diffusione
>>>>>>>>>>
>>>>>>>>>> e riproduzione è contraria alla legge e prego di darmi
>>>>>>>>>> prontamente avviso
>>>>>>>>>>
>>>>>>>>>> e di cancellare quanto ricevuto. Grazie.
>>>>>>>>>>
>>>>>>>>>> *
>>>>>>>>>> * For searches and help try:
>>>>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>>>>
>>>>>>>>> *
>>>>>>>>> * For searches and help try:
>>>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Le informazioni contenute in questa comunicazione e gli
>>>>>>>> eventuali documenti allegati
>>>>>>>>
>>>>>>>> hanno carattere confidenziale e sono a uso esclusivo del
>>>>>>>> destinatario. Nel caso
>>>>>>>>
>>>>>>>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>>>>>>>> che la sua diffusione
>>>>>>>>
>>>>>>>> e riproduzione è contraria alla legge e prego di darmi
>>>>>>>> prontamente avviso
>>>>>>>>
>>>>>>>> e di cancellare quanto ricevuto. Grazie.
>>>>>>>>
>>>>>>>> *
>>>>>>>> * For searches and help try:
>>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>>
>>>>>>> *
>>>>>>> * For searches and help try:
>>>>>>> * http://www.stata.com/help.cgi?search
>>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>>>>>
>>>>>>
>>>>>>
>>>>>> Le informazioni contenute in questa comunicazione e gli
>>>>>> eventuali documenti allegati
>>>>>>
>>>>>> hanno carattere confidenziale e sono a uso esclusivo del
>>>>>> destinatario. Nel caso
>>>>>>
>>>>>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>>>>>> che la sua diffusione
>>>>>>
>>>>>> e riproduzione è contraria alla legge e prego di darmi
>>>>>> prontamente avviso
>>>>>>
>>>>>> e di cancellare quanto ricevuto. Grazie.
>>>>>>
>>>>>> *
>>>>>> * For searches and help try:
>>>>>> * http://www.stata.com/help.cgi?search
>>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>>
>>>>> *
>>>>> * For searches and help try:
>>>>> * http://www.stata.com/help.cgi?search
>>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>>> * http://www.ats.ucla.edu/stat/stata/
>>>>
>>>>
>>>>
>>>> --
>>>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>>>
>>>>
>>>>
>>>> Le informazioni contenute in questa comunicazione e gli
>>>> eventuali documenti allegati
>>>>
>>>> hanno carattere confidenziale e sono a uso esclusivo del
>>>> destinatario. Nel caso
>>>>
>>>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>>>> che la sua diffusione
>>>>
>>>> e riproduzione è contraria alla legge e prego di darmi
>>>> prontamente avviso
>>>>
>>>> e di cancellare quanto ricevuto. Grazie.
>>>>
>>>> *
>>>> * For searches and help try:
>>>> * http://www.stata.com/help.cgi?search
>>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>>> * http://www.ats.ucla.edu/stat/stata/
>>>
>>> *
>>> * For searches and help try:
>>> * http://www.stata.com/help.cgi?search
>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>> * http://www.ats.ucla.edu/stat/stata/
>>
>>
>>
>> --
>> Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
>>
>>
>>
>> Le informazioni contenute in questa comunicazione e gli
>> eventuali documenti allegati
>>
>> hanno carattere confidenziale e sono a uso esclusivo del
>> destinatario. Nel caso
>>
>> questa comunicazione Vi sia pervenuta per errore, Vi informo
>> che la sua diffusione
>>
>> e riproduzione è contraria alla legge e prego di darmi
>> prontamente avviso
>>
>> e di cancellare quanto ricevuto. Grazie.
>>
>> *
>> * For searches and help try:
>> * http://www.stata.com/help.cgi?search
>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>> * http://www.ats.ucla.edu/stat/stata/
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/faqs/resources/statalist-faq/
> * http://www.ats.ucla.edu/stat/stata/
--
Rispetta l'ambiente: se non ti è necessario, non stampare questa mail
Le informazioni contenute in questa comunicazione e gli
eventuali documenti allegati
hanno carattere confidenziale e sono a uso esclusivo del
destinatario. Nel caso
questa comunicazione Vi sia pervenuta per errore, Vi informo
che la sua diffusione
e riproduzione è contraria alla legge e prego di darmi
prontamente avviso
e di cancellare quanto ricevuto. Grazie.
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/