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Marieke Stolte

Publications and source records attributed to Marieke Stolte.

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An Empirical Comparison of Methods for Quantifying the Similarity of Numeric Datasets

Methods for quantifying the similarity of datasets are relevant in applications where two or more datasets, or their underlying distributions, need to be compared, ranging from two- and k-sample testing to applications in machine learning and synthetic data generation. Many methods for quantifying the similarity of datasets are available from the literature, but due to the lack of neutral comparison studies, it is unclear which method to choose when. Here, 36 methods applicable to continuous data are compared across various scenarios, including two or more datasets drawn from different distributions. Several deviations between datasets are considered, including shift and scale alternatives or differences in higher moments. An overall method ranking is established based on the methods' abilities to differentiate between datasets from different distributions, combined with computational aspects. Based on this, concrete decision rules for finding the best method based on characteristics of the datasets are determined. Moreover, combinations of four to six methods are proposed in the two-sample case such that in 90% to 95% of the considered scenarios, at least one of these methods is almost as good as the best method. In the multi-sample case, a combination of two to three methods is proposed analogously.

stat.ME

An Empirical Comparison of Methods for Quantifying the Similarity of Categorical Datasets

Quantifying the similarity of two or more datasets has widespread applications in statistics and machine learning. The method choice is, however, difficult due to the abundance of proposed methods and the lack of neutral comparison studies, especially for categorical data. Here, the most promising methods are compared concerning their ability to detect certain differences between datasets and their resource consumption. The results show that the edge count tests perform well when comparing two datasets (i.e., the two-sample case). For certain scenarios, the constrained minimum (CM) distance performs even better. For categorical data consisting of variables with five categories each, the best method depends on the type of difference between the distributions, with either the CM distance and certain graph-based tests performing best, or the classifier-based tests (C2ST). This tendency is even clearer for multiple datasets. Overall, the Friedman-Rafsky test can be recommended for two samples as a compromise of high performance, acceptable resource consumption, and computational error occurrences. For the multi-sample case, the Multi-Sample Mahalanobis Cross-Match (MMCM) test can be recommended due to its comparably good performance and low resource consumption.

stat.ME

Methods for Quantifying Dataset Similarity: a Review, Taxonomy and Comparison

Quantifying the similarity between datasets has widespread applications in statistics and machine learning. The performance of a predictive model on novel datasets, referred to as generalizability, depends on how similar the training and evaluation datasets are. Exploiting or transferring insights between similar datasets is a key aspect of meta-learning and transfer-learning. In simulation studies, the similarity between distributions of simulated datasets and real datasets, for which the performance of methods is assessed, is crucial. In two- or $k$-sample testing, it is checked, whether the underlying distributions of two or more datasets coincide. Extremely many approaches for quantifying dataset similarity have been proposed in the literature. We examine more than 100 methods and provide a taxonomy, classifying them into ten classes. In an extensive review of these methods the main underlying ideas, formal definitions, and important properties are introduced. We compare the 118 methods in terms of their applicability, interpretability, and theoretical properties, in order to provide recommendations for selecting an appropriate dataset similarity measure based on the specific goal of the dataset comparison and on the properties of the datasets at hand. An online tool facilitates the choice of the appropriate dataset similarity measure.

stat.ME

Simulation study to evaluate when Plasmode simulation is superior to parametric simulation in estimating the mean squared error of the least squares estimator in linear regression

Simulation is a crucial tool for the evaluation and comparison of statistical methods. How to design fair and neutral simulation studies is therefore of great interest for researchers developing new methods and practitioners confronted with the choice of the most suitable method. The term simulation usually refers to parametric simulation, that is, computer experiments using artificial data made up of pseudo-random numbers. Plasmode simulation, that is, computer experiments using the combination of resampling feature data from a real-life dataset and generating the target variable with a known user-selected outcome-generating model (OGM), is an alternative that is often claimed to produce more realistic data. We compare parametric and Plasmode simulation for the example of estimating the mean squared error (MSE) of the least squares estimator (LSE) in linear regression. If the true underlying data-generating process (DGP) and the OGM were known, parametric simulation would obviously be the best choice in terms of estimating the MSE well. However, in reality, both are usually unknown, so researchers have to make assumptions: in Plasmode simulation for the OGM, in parametric simulation for both DGP and OGM. Most likely, these assumptions do not exactly reflect the truth. Here, we aim to find out how assumptions deviating from the true DGP and the true OGM affect the performance of parametric and Plasmode simulations in the context of MSE estimation for the LSE and in which situations which simulation type is preferable. Our results suggest that the preferable simulation method depends on many factors, including the number of features, and on how and to what extent the assumptions of a parametric simulation differ from the true DGP. Also, the resampling strategy used for Plasmode influences the results. In particular, subsampling with a small sampling proportion can be recommended.

stat.ME