User manual SPSS CONJOINT 8.0

[. . . ] SPSS Conjoint 8. 0 TM For more information about SPSS® software products, please visit our WWW site at http://www. spss. com or contact Marketing Department SPSS Inc. 233 South Wacker Drive, 11th Floor Chicago, IL 60606-6412 Tel: (312) 651-3000 Fax: (312) 651-3668 SPSS is a registered trademark and the other product names are the trademarks of SPSS Inc. No material describing such software may be produced or distributed without the written permission of the owners of the trademark and license rights in the software and the copyrights in the published materials. Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subdivision (c)(1)(ii) of The Rights in Technical Data and Computer Software clause at 52. 227-7013. [. . . ] If only a plan file or a data file is specified, the CONJOINT command reads the specified file and uses the working data file as the other. The plan file is specified with the PLAN subcommand, and the data file is specified with the DATA subcommand. For example, the command CONJOINT PLAN='CPLAN. SAV' /DATA='RUGRANKS. SAV' specifies that the plan file to be used in the conjoint analysis is cplan. sav, and the data file to be used in the analysis is rugranks. sav. To specify a plan file and use the current working data file as the data file, specify: CONJOINT PLAN='CPLAN. SAV' /DATA=* The asterisk (*) indicates that the working data file should be used as the data file. You can also eliminate the DATA subcommand altogether, and the working data file will automatically be used as the data file. Similarly, you can specify a data file and use the current working data file as the plan file. For example: CONJOINT PLAN=* /DATA='RUGRANKS. SAV' Specifying How Data Were Recorded You must specify the way in which preference data were recorded. Data can be recorded in one of three ways: sequentially, as rankings, or as preference scores. These 36 Chapter 4 three methods are indicated by the SEQUENCE, RANK, and SCORE subcommands. You must specify one, and only one, of these subcommands. SEQUENCE Subcommand The SEQUENCE subcommand indicates that data were recorded sequentially so that each data point in the data file is a profile number, starting with the most preferred profile and ending with the least preferred profile. This is how data are recorded if the subject is asked to order the profiles from the most to the least preferred. The researcher records which profile number was first, which profile number was second, and so on. The data in the carpet-cleaner study were recorded this way, as specified by the following syntax: CONJOINT PLAN='CPLAN. SAV' /DATA=* /SEQUENCE=PREF1 TO PREF22. RANK Subcommand The RANK subcommand indicates that each data point is a ranking, starting with the ranking of profile 1, then the ranking of profile 2, and so on. This is how the data are recorded if the subject is asked to assign a rank to each profile, ranging from 1 to n, where n is the number of profiles. For example, if the carpet-cleaner study had recorded data this way, and the variables in the study were named rank1 to rank22, it would be specified by the following syntax: CONJOINT PLAN='CPLAN. SAV' /DATA=* /RANK=RANK1 TO RANK22. SCORE Subcommand The SCORE subcommand indicates that each data point is a preference score assigned to the profiles, starting with the score of profile 1, then the score of profile 2, and so on. This type of data might be generated, for example, by asking subjects to assign a number from 1 to 100 to show how much they liked the profile. For example, if the carpet-cleaner study had recorded data this way, and the variables in the study were named score1 to score22, it would be specified by the following syntax: CONJOINT PLAN='CPLAN. SAV' /DATA=* /SCORE=SCORE1 TO SCORE22. 37 Analyzing Preferences: Using the Conjoint Procedure Optional Specifications In addition to the minimum required specifications, the CONJOINT command contains optional subcommands that allow you to specify a subject identification variable, specify a model for each factor, control analyses included in your output, and write a utility file to a specified file. SUBJECT Subcommand The SUBJECT subcommand allows you to specify a subject identification variable. If you do not specify a subject variable, the CONJOINT command assumes that all data come from one subject. In the carpet-cleaner study, the subject identification variable is named id, as specified with the following syntax: CONJOINT PLAN=CPLAN /DATA=* /SEQUENCE=PREF1 TO PREF22 /SUBJECT=ID FACTOR Subcommand The FACTOR subcommand allows you to specify the model describing the expected relationship between factors and the rankings or scores. The DISCRETE model indicates that the factor levels are categorical and that no assumption is made about the relationship between the factor and the scores or ranks. If you do not specify a model for a factor, CONJOINT assumes a discrete model. The LINEAR model indicates an expected linear relationship between the factor and the scores or ranks. [. . . ] · Profiles are written to an external file in single-profile format unless otherwise specified on the FORMAT subcommand. TITLE Subcommand TITLE specifies a string to be used at the top of the output in listing format or at the top of each new profile in profile format. · If TITLE is not used, no title appears above the first attribute. · The keyword TITLE is followed by a string enclosed in apostrophes. · Quotation marks can be used to enclose the string instead of apostrophes when you want to use an apostrophe in the title. [. . . ]