1. Advanced MMBR
Conjoint analysis (1)

2. Conjoint analysis -> Multi-level models
You have to understand:
What it is
Which different kinds of Conjoint Analysis there are
How it can be of use in typical TIW research
How it can lead to different kinds of statistical analyses (of the repeated measures or multi-level kind)
For this, you can use these slides AND the literature online
In the laptop exam, running a repeated measures analysis is part of the requirements.
Advanced Methods and Models in Behavioral Research

3. Advanced Methods and Models in Behavioral Research
The logic of the course
binary Y
 logistic regression
conjoint analysis: way of data collection that might come in handy
 "repeated measures" / "multi-level" data
We practice on self-collected data  some practice/training in survey design and execution
Advanced Methods and Models in Behavioral Research

4. Advanced Methods and Models in Behavioral Research
Conjoint Analysis
Underlying assumption: for
each user, the "utility" of a
product can be written as
U(x1,x2, ... , xn) = c0 + c1 x cn xn
10 Euro p/m
2 year minimum
free phone
...
How do you rate this
proposal? ( )
Advanced Methods and Models in Behavioral Research

5. Two kinds of research questions
Which phone do you prefer?
How do different attributes of a proposition affect the utility of a proposition?
Advanced Methods and Models in Behavioral Research

6. Why is this important?
It is an important tool in social science when you want to investigate how someone’s behavior depends on circumstances
and
a useful tool in typical TIW Master’s Theses -> examples will follow
It's not only of use in marketing!
Advanced Methods and Models in Behavioral Research

7. Advanced Methods and Models in Behavioral Research
One of the main advantages = more data: Example - Adoption of technology
If you ask for behavior only (“did you adopt” etc), then you get one piece of info per person, and the rest you have to infer by comparing different persons. -> OK, and gives “real” behavioral data, but data are sparse.
If you offer different scenarios and then ask whether someone would adopt, you get how adoption depends on the context for this person.
-> Richer data per person, but not behavioral
Given that sample sizes of >200 are often necessary, often option 2 is more feasible than option 1.
Advanced Methods and Models in Behavioral Research

8. Or, use it on ... medical decisions political decisions size of mole
color of mole
age of patient
patient in sun a lot
...
Is this skin cancer? ( )
medical decisions
strongly favor issue personally
core of party's strategy
many other parties against it
gets a lot of media attention
...
Do I submit a motion? ( )
political decisions
age 30-ish
high income (more than yours)
often away from home
lots of competition
probably prettier than you are
...

9. Example: properties of mobile phones
large b/w screen
long battery life
not flashy
costs 12 Euro/month
free
monthly contract
How do you rate this
option? ( )
Give each person 200 of these cases (“vignettes”)
Per person, run multiple regression on their 200 answers --> you get (personal) values for each of the dimensions.
You could then:
Create groups of people with the same kind of values, or …
… get an estimate of the average trade-off between dimensions, or …
… compare different groups of respondents
Suppose you get a
phone that has …
Advanced Methods and Models in Behavioral Research

10. The data would look like this:
NOTE
The D-values are chosen by the researcher -> experiment
200 is way too much
35 = 243 > 200
(or even: 410 = …)
If you look at the complete data set, this is repeated measures, with within-persons effects -> standard multiple regression will not work
Judgment: can people do this at all? Y D1 D2 D3 D4 D5 id … +4 -1 1 -3 +1
Other considerations
How many dimensions?
How many levels per dimension?
How many cases per person?
Which cases from all possible cases per person?
How many persons?
Judgment or choice?
Advanced Methods and Models in Behavioral Research

11. Advanced Methods and Models in Behavioral Research
Alternatives (1)
Ask people directly what their favorite phone is
If you could choose, which phone (and monthly plan) would you prefer?
+ much easier to collect
you will end up with as many suggestions as you have respondents
does not capture trade-offs between attributes
Advanced Methods and Models in Behavioral Research

12. Advanced Methods and Models in Behavioral Research
Alternatives (2)
Ask people directly for "their" utility model
For instance:
Which of the following factors do you find important when it comes to <buying a phone> / <adopting an innovation> / <deciding on whether a mole is malignant> / ...?
Please divide 100 points over the following factors:
- price
- battery life
- ...
+ much easier to collect
- asks for introspection about choice process
Advanced Methods and Models in Behavioral Research

13. A stupid example (with severe consequences)
“Compare these two glasses of water” (work in progress ...)
Advanced Methods and Models in Behavioral Research

14. Advantage of conjoint analysis (sophisticated)
Usually, the comparison of interest is within persons
person 1
person 2
person 3
person 4
person 5
But if you consider only the <sold phones >, you get the comparison between persons

15. Disadvantages of conjoint analysis
All fictituous decisions ("what would you do if ...")
(Often) assumes weighted average. This does not allow "all or nothing" weights
Can be quite complicated and/or boring for the respondents
Can be quite complicated for the researcher, both to implement and to analyze
...

16. Kinds of Conjoint Analysis
1. CVA: Conjoint Value Analysis
Choosing wisely from the set of all possible cases.
2. ACA: Adaptive Conjoint Analysis
Adapting the cases you offer based on previous answers of the respondent.
3. CBC: Choice Based Conjoint
Asking for preferences between 2 (or 3 or 4) cases.
4. PP-CBC: Partial-profile Choice Based Conjoint
Comparing only part of the attributes of the cases.
(This last one we disregard completely)
10 Euro p/m
2 year minimum
free phone
...
How do you rate this
proposal? ( )
Advanced Methods and Models in Behavioral Research

17. 1. CVA: Conjoint Value Analysis
Choosing wisely from the set of all possible cases.
Researcher chooses the dimensions
The variance of the multiple regression estimator equals
 (X’X)-1
(with X the matrix of D’s)
This implies that choosing the subset of cases that you are going to use, affects how broad your confidence intervals are.
-> Experimental design literature: full-factorial design, D-optimal designs, etc
Advanced Methods and Models in Behavioral Research

18. 2. ACA: Adaptive Conjoint Analysis
Adapting the cases you offer based on previous answers of the respondent.
You give, say, 10 cases to each respondent.
Which cases the respondent gets, depends on his answers to the first couple of cases.
Much more efficient than just randomly choosing cases
But
impossible to do off-line or by phone, and even online quite
difficult to implement
Advanced Methods and Models in Behavioral Research

19. 3. CBC: Choice Based Conjoint
Asking for preferences between 2 (or 3 or 4) cases.
Which of these three offers do you prefer? Or …
Rate these three offers Or …
Distribute 10 points over these 3 offers
10 Euro p/m
2 year minimum
free phone
internet = per Mb
15 Euro p/m
1 year minimum
phone costs 70
internet = per Mb
30 Euro p/m
2 year minimum
free phone
internet = free
Advanced Methods and Models in Behavioral Research

20. 3. CBC: Choice Based Conjoint (2)
Issues:
Which of these kinds of questions works best? We don’t know.
If you have only choice data (or ordinal data), how can you arrive at values for the different dimensions? Y D1 D2 D3 D4 D5 id
set 1 -1 2 … 3
Y = 0/1 => Logistic regression, but …
… that does not use all the available information and if we use the data for all persons we have dependencies in the data (more cases per person) and … what if we have ordinal data?
Advanced Methods and Models in Behavioral Research

21. Sawtooth software / SKIM Research
Creating the vignettes
Calculating the utility weights per person
Advanced Methods and Models in Behavioral Research

22. Which method to choose when?
We have rules of thumb only …
Advanced Methods and Models in Behavioral Research

23. Advanced Methods and Models in Behavioral Research
Sample size?
Difficult
... and you should understand why ...
Advanced Methods and Models in Behavioral Research

24. Statistical issues
We need to know how we can deal with “nested data” (for instance, more than one answer per person)
Can't the Sawtooth people take care of this?
Advanced Methods and Models in Behavioral Research

25. Marketing vs other social science
Marketing ("conjoint analysis")
Try to come up with the weights for each dimension for each respondent
(e.g. to then segment the population)
Other social science ("vignette study")
Try to come up with the average weights for groups of people
(so other aim, and you need less choices per person)

26. Advanced Methods and Models in Behavioral Research
To Do
Read and understand the literature on the course website on Conjoint Analysis.
Read the paper by Utz et al
me two logical follow up questions to this paper (and explain in a couple sentences why your choices make sense).
Advanced Methods and Models in Behavioral Research