Market Research: Foundations to Practice · Concept and Product Testing
Purchase Intent Scales and Their Limits
The standard 5-point purchase intent scale is one of the most widely used tools in concept testing, and also one of the most consistently misinterpreted. This chapter covers how it should actually be read.
Concept and product tests commonly use a standard 5-point purchase intent scale, ranging from 'definitely would not buy' to 'definitely would buy,' and the results are typically summarized as top-two-box (the percentage selecting either of the two most positive options) or top-box (the percentage selecting only the single most positive option) scores, rather than a simple average across the full numeric scale.
Key Takeaways
- Purchase intent is commonly measured on a 5-point scale, summarized as top-box or top-two-box percentages, not a simple average across the scale.
- Stated purchase intent systematically overstates actual purchase behavior, since survey responses carry no real money or genuine commitment.
- Purchase intent scores are best interpreted relative to category norms and historical benchmarks, since what counts as 'strong' varies by category and population.
- Intent scores are more reliable for relative ranking between concepts than for forecasting an absolute future sales volume or conversion rate.