First choice vs share of preference
First choice shows what the consumer picks first. Share of preference shows how preference is distributed. Which metric is right depends on the category's purchase behavior, and they often give entirely different answers.
In a simulation model, you can calculate market shares in two ways. The first-choice model gives the entire "vote" to the alternative the consumer prefers most. The share-of-preference model distributes preference proportionally — if a consumer likes A 60% and B 40%, A gets 0.6 and B gets 0.4 of that person's share.
The difference is not trivial. In categories with exclusive choice — where you buy one product at a time — first choice is often more realistic. In repertoire categories — where the consumer regularly buys several brands — share of preference reflects reality better. Using the wrong model produces systematically incorrect market share forecasts.
Reflect chooses simulation configuration based on the category's purchase behavior. We diagnose first: is this an exclusive choice category or a repertoire category? Then we configure the simulation model accordingly. It sounds obvious but it is rarely done in practice — most use the same model regardless of category.
Key takeaways
- First choice: the entire vote goes to the favorite, works for exclusive choice
- Share of preference: proportional distribution, works for repertoire buying
- Wrong model choice gives systematically incorrect market shares
- The category's purchase behavior determines which model is right
- Reflect diagnoses purchase behavior before configuring simulation
Example
The same conjoint data was analyzed with both models for a soft drink category. First choice gave the market leader 41% share. Share of preference gave 32%. Actual market share was 33% — the repertoire model was the right choice because consumers regularly vary their soft drink purchases.
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