Robust regression and outlier detection
Robust regression and outlier detection
Influence function and efficiency of the minimum covariance determinant scatter matrix estimator
Journal of Multivariate Analysis
Journal of Multivariate Analysis
Journal of Multivariate Analysis
The multivariate least-trimmed squares estimator
Journal of Multivariate Analysis
A simulation approach on Cronbach's alpha statistical significance
Mathematics and Computers in Simulation
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Cronbach's alpha is a popular method to measure reliability, e.g. in quantifying the reliability of a score to summarize the information of several items in questionnaires. The alpha coefficient is known to be non-robust. We study the behavior of this coefficient in different settings to identify situations where Cronbach's alpha is extremely sensitive to violations of the classical model assumptions. Furthermore, we construct a robust version of Cronbach's alpha which is insensitive to a small proportion of data that belong to a different source. The idea is that the robust Cronbach's alpha reflects the reliability of the bulk of the data. For example, it should not be possible that some small amount of outliers makes a score look reliable if it is not.