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Sequential Product Testing:
Minimizing Bias and Increasing Data Reliability

Taught by Dr. Benoît Rousseau and Dr. Daniel Ennis



Sequence effects introduce bias in product testing.  If not properly balanced, this bias can cause product means to be inaccurate and product comparisons to be misleading.  This is a well-known issue, but there has been a lack of good solutions to address it.  In this webinar we provide a general, computer intensive, approach to address this problem and also review current knowledge on sequential effects.

Using examples from actual consumer investigations we first illustrate how ratings for the same product, such as a beverage or a shampoo/conditioner bundle, can vary up to a full rating scale unit depending on its position in the design or the nature of the sample that precedes it.

We continue by focusing on three main rotation generation approaches: Order randomization within a subject, William Square designs, and the column randomization and search method or ‘CR&S’.  We compare these methods and show how CR&S is best equipped to minimize position, sequences, and sequence position biases.

We first discuss complete block designs and then extend our overview to more complex situations including multiple-day research and incomplete block designs.  In multiple-day applications, sequences between days are less relevant than those found within a day.  Incomplete designs will also be illustrated with optimal and near-optimal rotation sequence optimization.

Note: A software implementation of the CR&S method can be found in the IFPrograms® software.  Webinar participants not currently holding a subscription can request a two-month trial license to become more familiar with this design balancing method and see how it can help improve the quality of their sensory and consumer collected data.

This webinar is intended for a general audience of sensory professionals and graduate students. No detailed technical knowledge is assumed.

A digital recording of this webinar is available for purchase ($289). 


Attendance ($269)

Digital Recording ($289)

Attendance + Digital Recording ($359)

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