Fergadiotis Gerasimos, Kellough Stacey, Hula William D
J Speech Lang Hear Res. 2015 Jun 1;58(3):865-877. doi: 10.1044/2015_JSLHR-L-14-0249.
In this study, we investigated the fit of the Philadelphia Naming Test (PNT; Roach, Schwartz, Martin, Grewal, & Brecher, 1996) to an item-response-theory measurement model, estimated the precision of the resulting scores and item parameters, and provided a theoretical rationale for the interpretation of PNT overall scores by relating explanatory variables to item difficulty. This article describes the statistical model underlying the computer adaptive PNT presented in a companion article (Hula, Kellough, & Fergadiotis, 2015).
Using archival data, we evaluated the fit of the PNT to 1- and 2-parameter logistic models and examined the precision of the resulting parameter estimates. We regressed the item difficulty estimates on three predictor variables: word length, age of acquisition, and contextual diversity.
The 2-parameter logistic model demonstrated marginally better fit, but the fit of the 1-parameter logistic model was adequate. Precision was excellent for both person ability and item difficulty estimates. Word length, age of acquisition, and contextual diversity all independently contributed to variance in item difficulty.
Item-response-theory methods can be productively used to analyze and quantify anomia severity in aphasia. Regression of item difficulty on lexical variables supported the validity of the PNT and interpretation of anomia severity scores in the context of current word-finding models.
在本研究中，我们调查了费城命名测试（PNT；Roach、Schwartz、Martin、Grewal和Brecher，1996）对项目反应理论测量模型的拟合情况，估计了所得分数和项目参数的精度，并通过将解释变量与项目难度相关联，为PNT总分的解释提供了理论依据。本文描述了在一篇配套文章（Hula、Kellough和Fergadiotis，2015）中提出的计算机自适应PNT背后的统计模型。
我们使用存档数据评估了PNT对单参数和双参数逻辑模型的拟合情况，并检查了所得参数估计的精度。我们将项目难度估计值对三个预测变量进行回归：单词长度、习得年龄和语境多样性。
双参数逻辑模型的拟合略好，但单参数逻辑模型的拟合也足够。对于个体能力和项目难度估计，精度都很高。单词长度、习得年龄和语境多样性都独立地导致了项目难度的差异。
项目反应理论方法可有效地用于分析和量化失语症中的命名障碍严重程度。将项目难度对词汇变量进行回归，支持了PNT的有效性以及在当前词汇查找模型背景下对命名障碍严重程度分数的解释。
