Respondents’ use of information in choice modelling surveys

Bill Kaye-Blakea, Walt Abellb, and Eva Zellmana

aAgribusiness and Economics Research UnitbApplied Computing Group

Choice Modelling Workshop

Brisbane, 1-2 May 2008

Decision-making

• How people use information

• Theory – Simon, others

• Evidence

• Logit models derived from neoclassical paradigm

• Key question: does it make a difference?

Early attempt

• Paper survey with GM and non-GM alternatives

• Analysed choices– MNL, etc. (McFadden)

– Boundedly rational model (Simon)

• Results not brilliant

• Needed different data

Latest attempt

• Started from Hensher & Rose (debrief questions) and earlier BR work

• Teamed up with computer programmer and psychologist

• Computerised survey to capture information access

• Follow-up questions

Choice set display

Use of information

Unopened OpenedPercentage

unopened Group*

Texture 770 1840 29.5% a

Price 368 2242 14.1% b

Colour 815 1795 31.2% a

Production syst. 451 2159 17.3% c

Nutrition 434 2176 16.6% c

Country of origin 614 1996 23.5% d

* Similar within groups and statistically different between groups. Determined by chi-square tests, and are significant at the 0.01 level.

Figure 4. Respondent Behaviour During Survey

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Seconds to respond Number of attributes ignored

Models

• Two models– Assumed full information– Only accessed information

• Mixed logit– Random parameters based on significance

• Panel models

• For unused information: coded in Limdep as -888

ML: Assumed full informationParameters Derived St dev

Value St. err. Value St. err.

Floury -0.348 0.144* 0.869 0.160**

Organic 0.349 0.178* 0.972 0.186**

GM -2.46 0.331** 2.14 0.339**

Omega-3 0.898 0.217** 1.23 0.220**

Low-GI 0.383 0.191* 0.814 0.228**

Australia -0.613 0.172** 0.670 0.253**

China -1.43 0.219** 1.16 0.255**

Price -1.37 0.144**

Pink -0.000 0.000

Yellow 0.245 0.126

Partworths: Full informationAttribute

Partworth(NZ$/kg)

Standard deviation

Floury -0.252 0.373

Organic 0.262 0.419

GM -1.84 0.923*

Omega-3 0.666 0.526

Low-GI 0.276 0.349

Australia -0.447 0.291

China -1.05 0.497*

Price -1.00 0.0873**

Pink -2.75E-05 9.98E-05

Yellow 0.179 0.0545**

ML: Accessed informationParameters Derived St dev

Value St. err. Value St. err.

Floury 2.52E-03 1.00E-03* 3.07E-03 1.37E-03*

Organic 0.677 0.0684** 9.06E-04 2.61E-03

GM -0.676 0.0684** 7.32E-04 3.21E-03

Omega-3 0.0918 0.0592 8.82E-04 1.51E-03

Low-GI -0.0886 0.0591 6.26E-04 1.64E-03

Australia 0.307 0.0770** 1.13E-05 1.61E-03

China -0.305 0.0770** 2.81E-05 1.61E-03

Price 2.38E-03 6.42E-04**

Pink -0.203 0.0573**

Yellow 0.206 0.0573**

Findings

• All available information not used

• Controlling for information use changes parameters– ‘Australia’: – +

– Price: – ~0

• Unexplained heterogeneity largely disappears