TY - JOUR AU - Vandewalle, Vincent AU - Caron, Alexandre AU - Delettrez, Coralie AU - Périchon, Renaud AU - Pelayo, Sylvia AU - Duhamel, Alain AU - Dervaux, Benoit PY - 2020 DA - 2020/09/18 TI - Estimating the number of usability problems affecting medical devices: modelling the discovery matrix JO - BMC Medical Research Methodology SP - 234 VL - 20 IS - 1 AB - Usability testing of medical devices are mandatory for market access. The testings’ goal is to identify usability problems that could cause harm to the user or limit the device’s effectiveness. In practice, human factor engineers study participants under actual conditions of use and list the problems encountered. This results in a binary discovery matrix in which each row corresponds to a participant, and each column corresponds to a usability problem. One of the main challenges in usability testing is estimating the total number of problems, in order to assess the completeness of the discovery process. Today’s margin-based methods fit the column sums to a binomial model of problem detection. However, the discovery matrix actually observed is truncated because of undiscovered problems, which corresponds to fitting the marginal sums without the zeros. Margin-based methods fail to overcome the bias related to truncation of the matrix. The objective of the present study was to develop and test a matrix-based method for estimating the total number of usability problems. SN - 1471-2288 UR - https://doi.org/10.1186/s12874-020-01091-y DO - 10.1186/s12874-020-01091-y ID - Vandewalle2020 ER -