Using a scale (Chung & Nation, 2004)
Approaches to identifying specialised vocabulary for ESP
Developing and applying a scale-based approach to identifying specialised vocabulary in a text is a highly principled, if time-consuming, method. Chung and Nation (2003) used a scale to identify the technical vocabulary of an Anatomy textbook. The overall estimation was that at least one word in three in the Anatomy textbook was technical. In this method, the textbook is being used as a corpus, and lexical items are drawn out of the corpus analysis and then categorised according to a four-step scale. Chung and Nation (2003) outline the four steps in the scale that range from no connection to the field of Anatomy to words that only occur in that field and/or are unlikely to be known outside that field (see Table 2.3).
Table 2.3 Steps in the Chung and Nation (2003, p. 105) scale for Anatomy vocabulary
The researchers found that the majority of the technical vocabulary in the Anatomy textbooks was at step 4 of the scale (64.4%), meaning it was specific to the field and would be virtually unknown to people outside that field. A further 35.6% was at step 3, meaning it was closely related to Anatomy but could also occur in general English and in other fields.
Chung and Nation (2003) used the same scale approach on an Applied Linguistics textbook and found that approximately 20% of the lexis was technical. This means that two words in ten in a line of text are technical. This finding means that the Applied Linguistics textbook is more accessible than the Anatomy textbook. Around 88% of the Applied Linguistics technical vocabulary occurred in step 3, while only 11.6% was at step 4 of the scale (vocabulary unique to that subject area). This study is important because it shows that the amount of technical vocabulary can vary from subject to subject (in this case, from one word in three in Anatomy to one word in four in Applied Linguistics) and that there can be high levels of sharing between general English and other fields in areas such as Applied Linguistics and much less in areas such as Anatomy.
Categorising words, using a scale as in Chung and Nation’s (2004) study, may seem relatively straightforward, but it demands a great deal of time, skill, specialised knowledge of a field and decision making. A scale like this can be adapted so that teachers and students can decide which words they need to focus on in class or independent learning and why (see Coxhead, 2014a). Schmitt (2010) points out that perhaps the third and fourth steps in the scale are quite closely related. Any subjective method such as using a scale needs results to be checked by another rater — a process outlined clearly by Chung and Nation (2003).