A grounded procedure for managing data and sample size of a home medical device assessment

Simone Borsci, Jennifer L. Martin, Julie Barnett

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

    3 Citations (Scopus)


    The selection of participants for usability assessment, together with the minimum number of subjects required to obtain a set of reliable data, is a hot topic in Human Computer Interaction (HCI). Albeit, prominent contributions through the application of different p estimation models argued that five users provide a good benchmark when seeking to discover interaction problems a lot of studies have complained this five-user assumption. The sample size topic is today a central issue for the assessment of critical-systems, such as medical devices, because lacks in usability and, moreover, in the safety in use of these kind of products may seriously damage the final users. We argue that rely on one-size-fits-all solutions, such as the five-user assumption (for websites) or the mandated size of 15 users for major group (for medical device) lead manufactures to release unsafe product. Nevertheless, albeit there are no magic numbers for determining "a priori" the cohort size, by using a specific procedure it is possible to monitoring the sample discovery likelihood after the first five users in order to obtain reliable information about the gathered data and determine whether the problems discovered by the sample have a certain level of representativeness (i.e., reliability). We call this approach "Grounded Procedure" (GP).The goal of this study is to present the GP assumptions and steps, by exemplifying its application in the assessment of a home medical device.

    Original languageEnglish
    Title of host publicationHuman-Computer Interaction
    Subtitle of host publicationHuman-Centred Design Approaches, Methods, Tools, and Environments - 15th International Conference, HCI International 2013, Proceedings, Part I
    Number of pages10
    ISBN (Electronic)978-3-642-39232-0
    Publication statusPublished - 31 Jul 2013
    Event15th International Conference on Human-Computer Interaction, HCI International 2013 - Las Vegas, United States
    Duration: 21 Jul 201326 Jul 2013
    Conference number: 15

    Publication series

    NameLecture Notes in Computer Science
    ISSN (Print)0302-9743
    ISSN (Electronic)1611-3349


    Conference15th International Conference on Human-Computer Interaction, HCI International 2013
    Abbreviated titleHCI International
    Country/TerritoryUnited States
    CityLas Vegas
    Internet address


    • discovery likelihood
    • medical device
    • sample size
    • usability testing

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