Trial-Induced Demand Inflation in Conjoint Pretests: Experimental Identification via an Incumbent-Controlled Home-Use Trial
Output: full paper draft (84 pp) · Data: Müller Yogurt 2012 pre-launch conjoint with 3-arm home-use trial; Nielsen HMS · Recommended journal: Marketing Science (JMR as close second)
Consumer packaged goods firms routinely pair pre-launch conjoint studies with home-use product trials to forecast new-product demand, yet giving respondents free samples can inflate their stated willingness to buy independently of anything they learn about product quality. Because a new brand has no baseline awareness, standard pretests cannot separate genuine quality learning from trial-induced demand inflation. We isolate this bias experimentally using a three-arm randomized home-use trial conducted for Müller Yogurt's US launch, in which one control arm received a familiar, category-leading incumbent (Yoplait) where quality was already known. Merely receiving and trying the familiar incumbent inflates stated choice share by 16 to 19 percentage points—roughly twice the magnitude of typical hypothetical bias in consumer goods. Validating against post-launch scanner data, we show when debiasing improves volume forecasts and provide a simple pre-launch calibration benchmark.
Why this is a contribution
- It gives the first experimental benchmark for trial-induced bias in ASSESSOR/BASES-style pretests, which have relied on proprietary adjustments for fifty years. The source is a familiar incumbent arm, where post-trial lift reflects bias rather than learning.
- It sizes the bias: about +16–19 pp, at least +8 pp under worst-case attrition, and roughly twice the average hypothetical bias for consumer goods.
- It turns the result into a design diagnostic, η̂*: how much larger a new brand's inflation must be before the decomposition fails. Researchers can compute it when planning a pretest.
- It validates against actual launch data from Nielsen, and shows what bias correction does and does not buy for forecasting share.