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From |
Patty_FARE_Guelph Apichaya <pattria_ft@hotmail.com> |

To |
statalist <statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: calculate probability for clogit |

Date |
Fri, 23 Apr 2010 13:05:41 +0000 |

Hi, Could you give me an example? How I can code it for 2 choice? I tried to code it but the program doesn't work. asclogit choice price brand labeling, case(choiceset) alternative( alt_choice) variable alt_choice has replicate levels for one or more cases; this is not allowed I look at your code and looked at how they code data in webuse choice, clear. drop if car==3, is it mean I have to generate alternative 3 in the data set? because I have only 2alternatives. However, when I look at the data set of -clogit- and -asclogit-. They are the same. clogit choice price brand labeling, group(choiceset) I agree that the case or group variable in -clogit- I will use pair (choiceset). For example, I have 32 choice set and 1 choice set has pair of alternatives (optionA and B) This is that way that I code in my data set : choiceset alternatives 1 1 1 2 2 1 2 2 3 1 3 2 - - 32 1 32 2 1 1 1 2 2 1 2 2 3 1 3 2 - - 32 1 32 2 I will repeat the choice set again for next individual. Another point is should I continue choice set from 32 to 33 or should I repeat it from 1 to 32? Thank a lots Apichaya Lilavanichakul MSc. Candidate Department of Food Agricultural and Resource Economics Ontario Agricultural College University of Guelph Guelph, ON ---------------------------------------- > Date: Fri, 23 Apr 2010 08:10:17 -0400 > Subject: Re: st: calculate probability for clogit > From: sjsamuels@gmail.com > To: statalist@hsphsun2.harvard.edu > > I should never post to Statalist in the middle of the night. I > apologize for the brevity of the last message. > > -asclogit- worked for me in Stata 11 with two outcomes using the > choice data set. > > ******************** > webuse choice, clear > drop if car==3 > asclogit choice , casevars(sex) case(id) alternatives(car) > tab car, gen(car) > gen car2_sex =car2*sex //add interaction of person-level variable > with alternative > clogit choice car dealer car2_sex , group(id) //sex enters only in > interaction > ********************* > However I don't understand the pairwise design well-enough to be sure > of what you should do. One guess is that the case or group variable > should not be ID but "pair" and that to get proper standard errors you > should bootstrap the command with ID as a cluster variable for the > bootstrap. However, I think you need to consult somebody who knows > more about these analyses than I do. If you come back a correct > analysis in SAS, for example, we can probably help translate it into > Stata. > > Steve > > On Fri, Apr 23, 2010 at 12:54 AM, Steve Samuels wrote: >> Sorry, you are on your own. -asclogit- worked for me with two >> alternatives in Version 11 examples with the web "choice" data set., >> but perhaps there's something special about your data, or you did not >> have the proper format (2 records per person and option). You can >> get person-level variables into -clogit- by adding their interactions >> with your alternative variable. However you cannot use the -clogit- >> data format for -asclogit-. As I said this is not my area, so read >> the manual entries. >> >> Good luck. >> Steve >> >> On Thu, Apr 22, 2010 at 9:34 PM, Patty_FARE_Guelph Apichaya >> wrote: >>> Hi, >>> >>> I try to use -asclogit- but it has to have more than 2 alternatives in 1 choice set, so I cannot use this command in my analysis. >>> For the choice design, I use SAS software to design the pair of alternative and combination of factors in order to balance and give the optimal sets. I use clogit to analyze my choices and I want to know how I calculate probability the people choose each alternative in choice set. >>> >>> if I want to calculate personal factors, should I use -xtlogit- or which command it is appropriate? >>> >>> Thanks >>> >>> Apichaya Lilavanichakul >>> MSc. Candidate >>> Department of Food Agricultural and Resource Economics >>> Ontario Agricultural College >>> University of Guelph >>> Guelph, ON >>> >>> >>> >>>> Date: Tue, 20 Apr 2010 16:12:44 -0400 >>>> Subject: Re: st: calculate probability for clogit >>>> From: sjsamuels@gmail.com >>>> To: statalist@hsphsun2.harvard.edu >>>> >>>> I know almost nothing about discrete choice experiments, so please >>>> read the following comments with that in mind. >>>> >>>> 1. -asclogit- might be a better choice than -clogit-, as it will more >>>> easily include person-level variables like gender, income, and sex. >>>> >>>> 2. Your setup does not identify the individual in any way. The >>>> examples for -asclogit- and -clogit- all use the individual as the >>>> case or group variable. As "set" has only four levels, perhaps you can >>>> include it as a person-level variable. >>>> >>>> 3. The examples in -asclogit- consider alternatives based on one >>>> attribute (factor). You have three factors and these generate 12 (= >>>> 3 x 2 x 2) possible options, with 66 possible pairwise comparisons. >>>> You selected 32 of these, divided into four sets. I'm curious--is >>>> there a reference for this experimental design? Is the choice of >>>> comparisons and construction of the sets optimal or balanced in some >>>> sense? >>>> >>>> 4. For predicted probabilities, use the -pr- option in -asclogit- . >>>> >>>> Steve >>>> >>>> On Tue, Apr 20, 2010 at 9:39 AM, Patty_FARE_Guelph Apichaya >>>> wrote: >>>>> Hi all, >>>>> >>>>> I use STATA to analyze discrete choihce experiment. My choice design has 32 choice sets with each 2 options (A and B). Each option include 3 factors: price (13,15,17), brand (AA,BB), labeling (animal,plant). The choice set will look like this. >>>>> Option A OptionB >>>>> price 13 15 >>>>> brand AA BB >>>>> labeling animal plant >>>>> >>>>> From 32 choice sets is divide into 4 block with each 8 choice sets. Each individual (100 individuals) get 1 block (8 choice sets) and ask to choose between option A or B. >>>>> >>>>> choice = 1 chosen option, 0 not chosen option >>>>> set = same for two alternatives for each set i.e. there are 32 choice sets, it is repeated number from 1 to 32 and start it >>>>> again for the next 32 choice sets. >>>>> >>>>> This is the code; clogit choice price brand labeling, group(set) >>>>> >>>>> I also want to include individual characteristics; gender, income, age. how I can do it? >>>>> >>>>> How I can calculate the probability from people choosing choice? >>>>> >>>>> Any suggestion would be great. >>>>> Pat >>>>> >>>>> >>>>> _________________________________________________________________ >>>>> Hotmail has tools for the New Busy. Search, chat and e-mail from your inbox. >>>>> http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_1 >>>>> * >>>>> * For searches and help try: >>>>> * http://www.stata.com/help.cgi?search >>>>> * http://www.stata.com/support/statalist/faq >>>>> * http://www.ats.ucla.edu/stat/stata/ >>>>> >>>> >>>> >>>> >>>> -- >>>> Steven Samuels >>>> sjsamuels@gmail.com >>>> 18 Cantine's Island >>>> Saugerties NY 12477 >>>> USA >>>> Voice: 845-246-0774 >>>> Fax: 206-202-4783 >>>> >>>> * >>>> * For searches and help try: >>>> * http://www.stata.com/help.cgi?search >>>> * http://www.stata.com/support/statalist/faq >>>> * http://www.ats.ucla.edu/stat/stata/ >>> >>> _________________________________________________________________ >>> The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail. >>> http://www.windowslive.com/campaign/thenewbusy?tile=multicalendar&ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_5 >>> * >>> * For searches and help try: >>> * http://www.stata.com/help.cgi?search >>> * http://www.stata.com/support/statalist/faq >>> * http://www.ats.ucla.edu/stat/stata/ >>> >> >> >> >> -- >> Steven Samuels >> sjsamuels@gmail.com >> 18 Cantine's Island >> Saugerties NY 12477 >> USA >> Voice: 845-246-0774 >> Fax: 206-202-4783 >> > > > > -- > Steven Samuels > sjsamuels@gmail.com > 18 Cantine's Island > Saugerties NY 12477 > USA > Voice: 845-246-0774 > Fax: 206-202-4783 > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ _________________________________________________________________ The New Busy is not the old busy. Search, chat and e-mail from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_3 * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: calculate probability for clogit***From:*Steve Samuels <sjsamuels@gmail.com>

**References**:**st: calculate probability for clogit***From:*Patty_FARE_Guelph Apichaya <pattria_ft@hotmail.com>

**Re: st: calculate probability for clogit***From:*Steve Samuels <sjsamuels@gmail.com>

**RE: st: calculate probability for clogit***From:*Patty_FARE_Guelph Apichaya <pattria_ft@hotmail.com>

**Re: st: calculate probability for clogit***From:*Steve Samuels <sjsamuels@gmail.com>

**Re: st: calculate probability for clogit***From:*Steve Samuels <sjsamuels@gmail.com>

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