Abstract Keyword analysis is used in a range of sub-disciplines of applied linguistics from genre analyses to critically-oriented studies for different purposes ranging from producing a general characterization of a genre to identifying text-specific ideological issues. This study compares the use of log-likelihood (LL), a probability statistic, and odds ratio (OR), an effect size statistic, for keyword identification and argues that the two methods produce different keywords applicable to research focusing on different purposes. Through two case studies, keyword analyses of advance fee scams against the British National Corpus and research articles in applied linguistics against research articles from other academic disciplines, we show that both the LL and OR keywords concern the aboutness of the corpus, but differ in their specificity and pervasiveness through the corpus. LL highlights words which are relatively common in general use serving genre purposes, whereas OR highlights more specialized words serving critically-oriented purposes. Methodological and practical contributions to keyword analysis are discussed.

中文翻译：

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对数似然比和优势比：针对关键字分析不同目的的关键性统计

摘要关键字分析在应用语言学的各个子学科中使用，从体裁分析到面向批判性研究，其目的不同，从产生体裁的一般特征到识别特定文本的意识形态问题。这项研究比较了对数似然（LL）（概率统计量）和比值比（OR）（效果大小统计量）在关键字识别中的使用，并认为这两种方法产生了适用于不同目的研究的不同关键字。通过两个案例研究，针对英国国家语料库的预付款诈骗的关键字分析以及针对其他学术领域的研究语言的应用语言学研究文章的文章，我们显示LL和OR关键字均与语料库的相关性有关，但它们在语料库中的特异性和普遍性有所不同。LL突出显示通常用于体裁目的的相对较普遍的单词，而OR突出显示用于批评性目的的更专业的单词。讨论了对关键字分析的方法和实践贡献。