Some users need to pass in variable(s) to their Lighthouse survey, but don't have those data ahead of time so as to include them as Merged Variables in the password file. For example, some users choose to link respondents from a third-party interviewing software into a Lighthouse study and need to pass through and store the respondent ID so that the two datasets can later be merged. However, the respondent ID might be dynamically assigned in the third-party application and not known ahead of time.
The number of variables that can be passed into a Lighthouse study is limited only by the restriction imposed by browsers. Each can contain up to 255 characters of text.
Use the Pass-In Fields tab on the Questionnaire Access and Passwords dialog to specify any pass-in variables.
To pass in a variable, it must be included on the URL link that respondents click to access the survey. For example, the following link passes in two variables called ID and brandpref:
http://www.sawtoothsoftware.com/brd3/cgi-bin/ciwweb.pl?studyname=brd3&username=john&password=DGHQ&ID=42836290&brandpref=14
When the respondent clicks this link, it automatically starts the Lighthouse survey called brd3, provides a username and password, and saves the ID and brandpref values to the data for this respondent. The Start question (page 1) is bypassed and the first page the respondent sees is page 2. For more information about bypassing the starting page, please see One-Click Respondent Access to Survey.
(Note: be careful about specifying whether the pass-in field must be numeric only. If this restriction is in place and text is passed into the variable, an error is written to the log file.)