PDF(881 KB)
Nonparametric Diagnostic Classification for Polytomous Attributes: A Comparison of 18 Distance Discriminant Methods
Xu Huiying, Chen Qipeng, Liu Yaohui, Zhan Peida
Journal of Psychological Science ›› 2023, Vol. 46 ›› Issue (6) : 1486-1494.
PDF(881 KB)
PDF(881 KB)
Nonparametric Diagnostic Classification for Polytomous Attributes: A Comparison of 18 Distance Discriminant Methods
In the past decades, there has been increasing interests in cognitive diagnostic assessment (CDA) that allows identifying the mastery or non-mastery of specific fine-grained attributes required for solving problems in educational and psychological assessments. In the field of cognitive diagnosis, researchers have proposed a variety of methods to classify respondents into several classes according to their attribute patterns. In general, existing methods can be classified into two categories, including parametric and non-parametric diagnostic methods. Parametric diagnostic methods are based on psychometric models. For different test situations, the theoretical relationship between observed response pattern (ORP) and latent attribute vector is described by cognitive diagnosis models (CDM), such as the DINA model and its generalized models. In contrast, the distance discrimination method in non-parametric diagnostic methods generally assigns respondents directly to a latent category by minimizing the distance between the ORP and the ideal response pattern (IRP). The most important feature of non-parametric diagnostic methods is that they do not involve any CDM and can be computed at arbitrary sample sizes. Examples include the Hamming distance discriminant and the Manhattan distance discriminant.
However, the majority of current methods (both parametric and non-parametric diagnostic methods) assumes that attributes are binary variables (e.g., "0" for "non-mastery" and "1" for "mastery"). This "black-and-white" classification is too coarse and may not be able to meet the needs of refined measurement in practical scenarios. With the increasing demand for refined diagnosis, several CDMs with polytomous attributes have been proposed in recent years. However, non-parametric diagnostic methods have not yet touched on polytomous attributes, which leaves a gap for researchers and practitioners to understand the performance of non-parametric diagnostic methods in the diagnostic assessments with polytomous attributes.
To investigate the performance of non-parametric diagnostic methods in the diagnostic assessments with polytomous attributes, two simulation studies were conducted to compare the diagnostic classification accuracy of 20 non-parametric distance discrimination methods under different test conditions consisting of 5 independent variables, including sample size, item quality, test length, number of attribute levels, and number of attributes, and to compare them with a CDM with polytomous attributes. In simulation study 1, three independent variables were manipulated, including sample size (N = 30, 50, and 100), test length (I = 25 and 50), and item quality (IQ = high; i.e., the mean value of guessing and slipping is around. (1) And low (i.e., the mean value of guessing and slipping is around .(2) All 18 non-parametric methods were implemented using Python's SciPy package; the CDM with polytomous attributes was implemented using the full Bayesian MCMC algorithm. The weighted- and exact-attribute pattern correct classification rates were used to evaluate the classification accuracy. In simulation study 2, two independent variables were manipulated: the number of attributes (K = 3, 5, and 7) and the number of attribute levels (Lk = 3 and 5). The sample size was fixed as 100, the test length was fixed as 50, and the item quality was fixed as high, respectively. All other conditions were consistent with simulation study 1.
The results of studies indicated that: (1) The effect of sample size on the classification accuracy of all non-parametric methods was small; (2)The classification accuracy of non-parametric methods increased with increasing item quality and test length, but decreased with the increasing number of attributes and number of attribute levels; and (3) In two simulation studies, the performance of the 18 non-parametric distance discrimination methods was robust across all test conditions, with the 8 distances of Canberra, Manhattan, Euclidean, Seuclidean, Sqeuclidean, Minkowski, Hamming, and Sokal-Michener dissimilarity distance discrimination methods performing relatively better. (4) In empirical study, the classification findings of the majority of nonparametric distance discriminant approaches match well with the RPa-DINA model.
In conclusion, this study is the first attempt to explore the performance of non-parametric diagnostic methods in the diagnostic assessments with polytomous attributes, which expands the application of non-parametric diagnostic methods and enriches the data analysis methods for polytomous attributes.
cognitive diagnosis / polytomous attributes / non-parametric cognitive diagnosis / distance discrimination / hamming distance / euclidean distance / Manhattan distance
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