TY - JOUR A1 - Fellinghauer, Carolina Saskia A1 - Prodinger, Birgit A1 - Tennant, Alan T1 - The Impact of Missing Values and Single Imputation upon Rasch Analysis Outcomes: A Simulation Study JF - Journal of Applied Measurement N2 - Imputation becomes common practice through availability of easy-to-use algorithms and software. This study aims to determine if different imputation strategies are robust to the extent and type of missingness, local item dependencies (LID), differential item functioning (DIF), and misfit when doing a Rasch analysis. Four samples were simulated and represented a sample with good metric properties, a sample with LID, a sample with DIF, and a sample with LID and DIF. Missing values were generated with increasing proportion and were either missing at random or completely at random. Four imputation techniques were applied before Rasch analysis and deviation of the results and the quality of fit compared. Imputation strategies showed good performance with less than 15% of missingness. The analysis with missing values performed best in recovering statistical estimates. The best strategy, when doing a Rasch analysis, is the analysis with missing values. If for some reason imputation is necessary, we recommend using the expectation-maximization algorithm. KW - Local item dependencies (LID) KW - Differential item functioning (DIF) KW - Imputation techniques KW - Rasch analysis Y1 - 2018 VL - 19 IS - 1 SP - 1 EP - 25 PB - JAM Press ER - TY - JOUR A1 - Adroher, Núria Duran A1 - Prodinger, Birgit A1 - Fellinghauer, Carolina Saskia A1 - Tennant, Alan ED - Public Library of Science, T1 - All metrics are equal, but some metrics are more equal than others: A systematic search and review on the use of the term 'metric' JF - PLoS One N2 - Objective: To examine the use of the term ‘metric’ in health and social sciences’ literature, focusing on the interval scale implication of the term in Modern Test Theory (MTT). Materials and methods: A systematic search and review on MTT studies including ‘metric’ or ‘interval scale’ was performed in the health and social sciences literature. The search was restricted to 2001–2005 and 2011–2015. A Text Mining algorithm was employed to operationalize the eligibility criteria and to explore the uses of ‘metric’. The paradigm of each included article (Rasch Measurement Theory (RMT), Item Response Theory (IRT) or both), as well as its type (Theoretical, Methodological, Teaching, Application, Miscellaneous) were determined. An inductive thematic analysis on the first three types was performed. Results: 70.6% of the 1337 included articles were allocated to RMT, and 68.4% were application papers. Among the number of uses of ‘metric’, it was predominantly a synonym of ‘scale’; as adjective, it referred to measurement or quantification. Three incompatible themes ‘only RMT/all MTT/no MTT models can provide interval measures’ were identified, but ‘interval scale’ was considerably more mentioned in RMT than in IRT. Conclusion: ‘Metric’ is used in many different ways, and there is no consensus on which MTT metric has interval scale properties. Nevertheless, when using the term ‘metric’, the authors should specify the level of the metric being used (ordinal, ordered, interval, ratio), and justify why according to them the metric is at that level. KW - Metrics KW - MTT assay KW - Database Searching KW - Psychometrics Y1 - 2018 UR - https://doi.org/10.1371/journal.pone.0193861 VL - 13 IS - 3 SP - e0193861 ER -