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A latent class analysis on the usage of mobile phones among management students

100%
Kumar S., Dabgotra A. V.
Statistics in Transition new series
|
2021
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vol. 22
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issue 1
89-114
EN
In the past few years, wireless devices, including pocket PCs, pagers, mobile phones, etc, have gained popularity among a variety of users across the world and the use of mobile phones in particular, has increased significantly in many parts of the world, especially in India. Cell phones are now the most popular form of electronic communication and constitute an integral part of adolescents' daily lives, as is the case for the majority of mobile phone users. In fact, mobile phones have turned from a technological tool to a social tool. Therefore, the influence of cell phones on young people needs to be thoroughly examined. In this paper, we explore the attitude of young adults towards cell phones and identify the hidden classes of respondents according to the patterns of mobile phone use. The Latent Class Analysis (LCA) serves as a tool to detect any peculiarities, including those gender-based. LCA measures the value of an unknown latent variable on the basis of the respondents' answers to various indicator variables; for this reason, a proper selection of indicators is of great importance here. In this work, we propose a method of selecting the most useful variables for an LCA-based detection of group structures from within the examined data. We apply a greedy search algorithm, where during each phase the models are compared through an approximation to their Bayes factor. The method is applied in the process of selecting variables related to mobile phone usage which are most useful for the clustering of respondents into different classes. The findings demonstrate that young people display various feelings and attitudes toward cell phone usage.
2
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Hierarchical Log-linear Models for Contingency Tables

51%
Brzezińska J.
Acta Universitatis Lodziensis. Folia Oeconomica
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2012
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vol. 269
EN
Log-linear models are widely used for qualitative data in multidimensional contingency tables. Hierarchical log-linear models are models that include all lower-order terms composed from variables contained in a higher-order model term. The starting point is a saturated model, then homogenous associations, conditional independence and complete independence. There are several statistics that help to choose the best model. The first is the likelihood ratio approach, next is AIC and BIC information criteria. In R software there is loglm() function in MASS library and glm in stats library. The first approach is presented in this paper
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On an Improvement of the Model-Based Clustering Method

38%
Witek E., ent. Department of Statistics T. K. A. U. o. E.
Acta Universitatis Lodziensis. Folia Oeconomica
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2009
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vol. 228
PL
W artykule przedstawiona została modyfikacja metody taksonomii opartej na modelach mieszanych, w przypadku gdy niemożliwym staje się oszacowanie parametrów modelu za pomocą algorytmu EM. Gdy liczba obiektów przypisanych do klasy jest mniejsza niż liczba zmiennych opisujących te obiekty, niemożliwym staje się oszacowanie parametrów modelu. By uniknąć tej sytuacji estymatory największej wiarygodności zastępowane są estymatorami o największym prawdopodobieństwie a posteriori. Wybór modelu o najlepszej parametryzacji i stosownej liczbie klas dokonywany jest wówczas za pomocą zmodyfikowanej statystyki BIC.
EN
An improvement o f the model-based clustering (MBC) method in the case when EM algorithm fails as a result o f singularities is the basic aim o f this paper. Replacement o f the maximum likelihood (MLE) estimator by a maximum a posteriori (MAP) estimator, also found by the EM algorithm is proposed. Models with different number o f components are compared using a modified version o f BIC, where the likelihood is evaluated at the MAP instead o f MLE. A highly dispersed proper conjugate prior is shown to avoid singularities, but when these are not present it gives similar results to the standard method o f MBC.
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