Quality of measurement in core lexicon (Kim et al., 2022)

<strong>Purpose: </strong>Core lexicon measures have received growing attention in research. They are intended to provide clinicians with a clinician-friendly means to quantify word retrieval ability in discourse based on normal expectations of discourse production for specific discourse elicitation tasks. To date, different criteria have been used to develop core lexicon measures by groups of researchers. The need for statistical guidance in pursuit of the psychologically robust measure has been recognized. <strong>Aims: </strong>This study was to investigate the best criterion for accurate measurement. Specifically, we focused on two criteria (<em>frequency </em>vs. <em>percentage</em>) that have previously been used for the development of core lexicon measures. <strong>Method:</strong> Core lexicon measures consisting of five different checklists by word class (verbs, nouns, adjectives, adverbs, and function words) and developed by the two criteria were applied to language samples produced by 470 cognitively healthy adults. Performance in word retrieval ability at the discourse level was modeled as a latent variable based on the observed proportions of the production of core lexicon items in two different sets of core lexicon measures using structural equation modeling. <strong>Results: </strong>Results indicated that both criterion for core lexicon measures capture word retrieval ability in discourse. Greater residual variances were found in the core lexicon measure established by the percentage criterion compared to the one established by the frequency criterion. This indicates that the measure based on the percentage criterion is more affected by measurement errors. <strong>Conclusions: </strong>The findings provide evidence that the frequency criterion is better to use for the development of core lexicon measures for core nouns, verbs, adjectives, and adverbs, but not for function words. However, our findings are limited to core lexicon measures based on language samples elicited by wordless picture books. This may not be easily applied to other core lexicon measures that use different discourse elicitation tasks due to the difference in quality and quantity of language samples. Ideally, the same approach should be replicated to evaluate the appropriateness of respective criteria in the development of core lexicon measures. <br> <strong>Supplemental Material S1. </strong>Core Lexicon checklists for <em>Good Dog, Carl</em> and <em>Picnic </em>developed by frequency and percentage criteria. <br> <strong>Supplemental Material S2. </strong>Mean number of different words/words produced by age and story (<em>Good Dog, Carl </em>[GDC], <em>Picnic</em>). <br> Kim, H., Schoemann, A. M., &amp; Wright, H. H. (2022). Quality of measurement in core lexicon measures.<em> Journal of Speech, Language, and Hearing Research</em>. Advance online publication. https://doi.org/10.1044/2022_JSLHR-20-00722

**研究背景**：核心词汇量测量（core lexicon measures）在研究领域受到日益广泛的关注。此类工具旨在为临床医师提供一种临床友好型手段，基于特定语篇诱发任务下的正常语篇产出预期，量化个体在语篇中的词汇提取能力。迄今为止，不同研究团队已采用多种标准开发核心词汇量测量工具。学界已认识到，在开发心理测量学稳健的测量工具时，亟需统计学方法的指导。

**研究目标**：本研究旨在探究适用于精准测量的最优标准，重点聚焦此前用于开发核心词汇量测量的两类标准：频次（frequency）与占比（percentage）。

**研究方法**：本研究采用基于两类标准开发的、按词类（动词、名词、形容词、副词及功能词）划分的5套独立核查表组成的核心词汇量测量工具，对470名认知健康成年人的语言样本进行施测。以两套不同核心词汇量测量工具下核心词汇项目产出的观测占比为指标，通过结构方程模型（structural equation modeling）将语篇层面的词汇提取能力建模为潜变量。

**研究结果**：结果表明，两类标准开发的核心词汇量测量工具均可有效捕捉语篇中的词汇提取能力。相较于基于频次标准开发的测量工具，基于占比标准开发的测量工具呈现出更高的残差方差，这意味着基于占比标准的测量工具受测量误差的影响更为显著。

**研究结论**：本研究结果显示，针对名词、动词、形容词及副词的核心词汇量测量工具开发，采用频次标准更为适宜，但该结论并不适用于功能词。不过本研究的结论仅适用于以无字图画书（wordless picture books）诱发的语言样本构建的核心词汇量测量工具，由于不同语篇诱发任务下语言样本的质量与数量存在差异，该结论难以直接推广至采用其他语篇诱发任务的核心词汇量测量工具。未来应采用相同研究范式开展重复验证，以评估各类标准在核心词汇量测量工具开发中的适用性。

**补充材料S1**：基于频次与占比标准开发的《好狗，卡尔（Good Dog, Carl）》与《野餐（Picnic）》核心词汇核查表。

**补充材料S2**：按年龄与故事类型（《好狗，卡尔》[GDC]、《野餐》）划分的不同词汇产出数与总词汇产出数均值。

**参考文献**：Kim, H., Schoemann, A. M., & Wright, H. H. (2022). 核心词汇量测量工具的测量质量. 《言语、语言与听力研究杂志（Journal of Speech, Language, and Hearing Research）》. 网络提前出版. https://doi.org/10.1044/2022_JSLHR-20-00722