Design of vignettes

Question

Good afternoon,
I have a question concerning a questionnaire design.
I would like to implement a vignette study in which each vignette is composed of three different independent variables (a,b,c) , having two levels each.(a1/a2, b1/b2, c1/c2).
Accordingly 8 different combinations of those independent variables/vignettes are possible.
(a1,b1,c1);(a1,b2,c1);(a1,b1,c2);(a1,b2,c2)......
Unfortunately I am not sure how I can implement a questionnaire design, in which each respondent evaluates all 8 potential combinations individually but according to the same question (Ideally the order of those combinations would be randomized). I already found a design allowing for such combinations of independent variables, but unfortunately one could only ones draw from this urn of combinations. Is there any option to draw from this urn of 8 potential combinations on different pages ? Subsequently I would like to analyze the date with an ANOVA analysis.

Thank you very much in advance !

Answer 1

questionnaire design, in which each respondent evaluates all 8 potential combinations individually but according to the same question

There are multiple options to implement such a design. The easiest would be the following one:

1) Create 8 copies of that quastion, adjust the content to present one vignette per question

2) Place these questions on 8 different pages

3) Rotate the page order.

You could as well work with with placeholders or question rotation, but the above solution is the least abstract one in my opinion.

Comments

> Please evaluate the product on the following scale (1=very bad...7=very good).

Well, in this case I would recommend to simply put the product description (pimped with HTML) as text or instruction into a scale question (plus one Item for the rating, you can set to display this in a single line).

You definitely won't need prepare_input() or %input:...% to implement this design :)

>  in order to activate the internal variables, which how I understood it subsequently allows me to measure their influence on the rating.

You do not "measure" the influence, but infer it from patterns in the data. What you do when you're data is collected is to compute a regression model to estimate the influence of each variable on the rating.

What you need for that is either a multi-level design (a bit overcomplex for that) or a restructured data set with one column for the product (was: variable number), one for the rating, and one for the CASE number, e.g.

1  7  123
2  5  123
3  6  123
4  7  123
...
1  5  124
2  6  124
3  2  124
...

And then in SPSS you recode the 1 to 8 in the first colum into 3 variables describing your independent variables. That's all you need to compute the regression model.

If we find some time, we will implement a conjoint module. But as long as this is done, it's not that hard to realize.

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That sounds like my (research) life just got way easier.

Accordingly I could just implement the study like this:
- I prepare a textblock for each potential variable level (e.g one for price high, one for service high, one for speed low...)
- I prepare 8 times the same rating questions (scale ranging from 1-7)

Subsequently I place on each page:
- three textblocks, each of one variable, to achieve the specific combination of price, service, speed
- one of the 8 question copies measuring the product evaluation on a scale of (1-7)

This I repeat until all 8 combinations of variables are in the questionnaire.

After the respondents answered I can restructure the data I received, in order to analyze the individual influence of for example price high on the product evaluation. So finally this allows me to achieve similar data like from a multilevel analysis?

And thank you for your fast answers, you are amazing !

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> - I prepare a textblock for each potential variable level (e.g one for price high, one for service high, one for speed low...)

Not exactly. What you do is to prepare a question (with text) for each combinatin/vignette that contains all three variables in the text.

>  I place on each page:
> - three textblocks

Yes, you could also create it this way. But honestly: It will look better if you put it all into one HTML code.

> This I repeat until all 8 combinations of variables are in the questionnaire.

Correctly. Then you should have 8 pages for the 8 vignettes. And if you like (you should!) you use setPageOrder() one one page before the first vignette to rotate the pages.

> After the respondents answered I can restructure the data I received, in order to analyze the individual influence of for example price high on the product evaluation.

Exactly. But try this procedure after you have collected some data in the pretest. Just to be sure - and you don't want to do that when you're close to the deadline.

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Not exactly. What you do is to prepare a question (with text) for each combinatin/vignette that contains all three variables in the text.

--> So I would just put the text describing my vignette in the field 'Frage-Text', unfortunately I didnt find there the option how to edit this part of the text as a html.

Or do I add the text separately via 'Text hinzufügen' and hence create 8 texts for the 8 vignettes  and just put the text of one vignette on top of one of the 8 scales measuring the product evaluation.

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> unfortunately I didnt find there the option how to edit this part of the text as a html.

Just type HTML code :)

You can, of course, use separate texts and questions as well. However, this is unnecessarily complex in my opinion.