Given the importance of vocabulary knowledge for successful uses of language in various contexts, identifying the vocabulary learning needs of language learners has been a consistent concern for vocabulary researchers working in applied linguistics. In this regard, in a widely employed classification, the vocabulary of English has been divided into four categories of high-frequency (or general service), academic, technical, and low-frequency words (Coxhead & Nation, 2001; Nation, 2001). It has been argued that in a well-balanced course, English language learners should move from general service words to the academic and technical vocabulary. Within this traditional view on vocabulary learning/teaching (for more recent views, see: Beck et al., 2013; Nation, 2013; Schmitt & Schmitt, 2014; Vilkaitė-Lozdienė & Schmitt, 2019), academic vocabulary has been operationalized very broadly as the words that occur with reasonably higher frequency across different academic genres (such as research articles), but are much less frequent in other text types (Coxhead & Nation, 2001). Previous research indicated that this vocabulary type accounts for around 10 to 14 percent of most academic texts (Coxhead, 2000; Gardner & Davies, 2014), and learning such words in particular poses a major challenge for English language learners studying in a university context (Coxhead, 2000, 2011, 2018b, 2019; Coxhead & Nation, 2001; Nation & Waring, 1997; Xue & Nation, 1984). The Academic Word List (AWL) (Coxhead, 2000) which was developed more than two decades ago aimed to help university students and their instructors in dealing with academic vocabulary. This core academic word list contains 570 word families, and despite some limitations remained as a main source for EAP instruction, materials development, and vocabulary assessment (Coxhead, 2011; Huntley, 2006; McLean & Kramer, 2015; Wells, 2007).
Over the past years, a growing number of corpus-based studies investigated academic vocabulary in different text types, including research articles (Coxhead, 2018b, 2019; Dang, 2019). This line of research generally aims to help English for Academic Purposes (EAP) instructors and students to set better and more informed vocabulary learning goals. A significant finding attained from this growing body of literature is the fact that the use of academic vocabulary shows considerable variation among different disciplines and subject areas (Chen & Ge, 2007; Green & Lambert, 2018; Khani & Tazik, 2013; Lei & Liu, 2016; Liu & Han, 2015; Martínez et al., 2009; Valipouri & Nassaji, 2013; Valizadeh & Xodabande, 2021; Wang et al., 2008; Xodabande & Xodabande, 2020). It has been also highlighted that there is a need for creating more restricted and discipline-specific word lists to account for the needs to university students (Durrant, 2014, 2016; Hyland & Tse, 2007). Moreover, with the increased importance of corpus-based approaches in language education (Boulton & Cobb, 2017; Braun, 2007; Chambers, 2019; Farr & O’Keeffe, 2019; Römer, 2011; Vyatkina, 2020), research in English for Specific Purposes (ESP) vocabulary studies is attracting more attention (Coxhead, 2018b; Nation, 2016). Nevertheless, against this promising scholarship, a missing component in vocabulary studies is the scarcity of replication research, and the number of replicated studies remained very limited (Coxhead, 2018a, 2018b; N. Schmitt et al., 2017).
Replication refers to the exact or approximate repetition of the earlier studies that aim to determine if the reported findings are reliable and generalizable (Abbuhl, 2018; Marsden et al., 2018; Porte & McManus, 2019; Siyanova-Chanturia, 2014). Although the excessive prioritization of originality and innovation in applied linguistics over the past decades negatively impacted conducting replication research within the field (Abbuhl, 2018), recent years have witnessed a growing interest in replication studies (Marsden et al., 2018). It has been also argued that replication is critical in word list research (Miller & Biber, 2015). Accordingly, there is a need to repeat earlier studies focusing on specialized vocabulary with different but similar corpora to see if the same items would be generated for other lists (Coxhead, 2018b). Given that the use of the AWL items in applied linguistics research articles was examined in the past decades (Khani & Tazik, 2013; Vongpumivitch et al., 2009), the current study aimed to replicate those studies by following the same procedures, but with analyzing a much larger and more representative corpus. The following section provides a general overview of the studies that investigated the use of the AWL in a number of disciplines. The discussion then turns to the two studies that the current study aimed to replicate.