Measuring Whether Product Change Still Meets Consumer Expectations
The development of the Degree of Satisfaction-Difference (DOSD) method
A reference-based approach to measuring how consumer evaluation changes — and whether the changed product still meets the criterion that matters.
The Challenge
Consumer acceptance is often measured through liking scores. These are useful, but their meaning is not necessarily the same for every consumer, and ratings can shift with the experimental context.
For reformulation and quality-maintenance decisions, the key question is often not simply:
Do consumers like the changed product?
It is:
Does the product still deliver what consumers expect — and how much has their evaluation changed relative to the current product?
This was the problem addressed in the development of the Degree of Satisfaction-Difference method, developed by Professor Hye-Seong Lee and colleagues at Ewha Womans University in collaboration with our internal consumer science team.
The idea behind DOSD
DOSD combines several elements designed to help consumers evaluate product change more consistently.
The method starts with a product-specific cognitive warm-up, prompting consumers to think about what matters to them when choosing and using the product. The aim is to activate their own expectations and evaluation criteria before testing begins.
During the test, a meaningful reference product is presented before each test product. This helps consumers maintain a more stable frame of reference. The reference is also included blind among the test samples, providing information about response variability when consumers are effectively evaluating the same product.
Rather than relying only on an isolated numerical rating, consumers make criterion-based judgements, originally focused on satisfaction relative to the reference.
What the validation showed
The method was tested by placing the same product comparison within two different product ranges.
With conventional hedonic scaling, part of the consumer sample produced different conclusions depending on the surrounding products.
With DOSD, the same comparison remained consistent across the two contexts.
This suggests that the combined design — cognitive warm-up, reference-based evaluation and structured response format — can provide a more stable basis for measuring subtle changes in consumer evaluation.
Two questions, not one
One of the most useful aspects of DOSD is that it separates two questions that are often treated as if they were the same:
How much has consumer evaluation changed relative to the current product?
and
Does the changed product still meet the consumer criterion?
Using Signal Detection Theory, the comparative response can be expressed as d′, an effect-size measure describing the direction and magnitude of change relative to the reference. Later work also explored absolute satisfaction measures, providing a complementary view of whether a product is judged satisfactory in its own right.
This distinction matters because a product can be judged differently from the reference without necessarily becoming unacceptable.
From scores to decision-relevant evidence
A mean rating tells us where a product falls on a scale, but not automatically what that score means for each individual consumer.
A score of 7, for example, may be perfectly acceptable to one person, while another may require an 8 before considering the product good enough.
A criterion-based approach makes that boundary more explicit. It can therefore provide information about both:
the magnitude and direction of the change, and
the proportion of consumers meeting the defined criterion.
The original DOSD studies used satisfaction because it relates the product experience to consumer expectations. The same principle can also be applied to other clearly defined criteria, such as acceptance, suitability or a consumer-relevant sensory or functional judgement, particularly where there is a meaningful threshold.
Where DOSD fits
DOSD is not intended to replace hedonic scaling.
Hedonic data remain valuable for understanding the broader acceptance landscape. DOSD adds a different layer of evidence when the decision concerns tolerance to product change, robustness relative to a reference, and whether a consumer criterion is still being met.
It is particularly relevant when product differences are small to moderate and the business decision depends on understanding the risk associated with change.
