Corpus-assisted discourse studies, or CADS, is related historically and methodologically to the discipline of corpus linguistics. The principal endeavor of corpus-assisted discourse studies is the investigation, and comparison of features of particular discourse types, integrating into the analysis the techniques and tools developed within corpus linguistics. These include the compilation of specialised corpora and analyses of word and word-cluster frequency lists, comparative keyword lists and, above all, concordances.

A broader conceptualisation of corpus-assisted discourse studies would include any study that aims to bring together corpus linguistics and discourse analysis. Such research is often labelled as corpus-based or corpus-assisted discourse analysis, with the term CADS coined by a research group in Italy for a specific type of corpus-based discourse analysis.

Aims

Corpus-assisted discourse studies aim to uncover non-obvious meaning, that is, meaning which might not be readily available to naked-eye perusal. Much of what carries meaning in texts is not open to direct observation: “you cannot understand the world just by looking at it” (Stubbs [after Gellner 1959] 1996: 92). We use language “semi-automatically”, in the sense that speakers and writers make semi-conscious choices within the various complex overlapping systems of which language is composed, including those of transitivity, modality (Michael Halliday 1994), lexical sets (e.g. freedom, liberty, deliverance), modification, and so on. Authors themselves are, famously, generally unaware of all the meanings their texts convey. By combining the quantitative research approach, that is, statistical analysis of large amounts of the discourse in question - more precisely, large numbers of tokens of the discourse type under study contained in a corpus - with the more qualitative research approach typical of discourse analysis, that is, the close, detailed examination of particular stretches of discourse it may be possible to better understand the processes at play in the discourse type and to gain access to non-obvious meanings.

Aims can differ in other types of corpus-based or corpus-assisted discourse analysis; but in general such studies combine quantitative and qualitative research and aim to shed light on discourses, registers, discourse patterns, etc., with the help of a corpus linguistic approach. Specific aims and techniques depend on the relevant project.

CADS as a specific type of corpus-based discourse analysis

Researchers in Italy have developed CADS as a specific type of corpus-based discourse analysis, creating a standard set of methods:

'A basic, standard methodology in CADS may resemble the following:'

Step 1: Decide upon the research question;

Step 2: Choose, compile or edit an appropriate corpus;

Step 3: Choose, compile or edit an appropriate reference corpus / corpora;

Step 4: Make frequency lists and run a keywords comparison of the corpora;

Step 5: Determine the existence of sets of key items;

Step 6: Concordance interesting key items (with differing quantities of co-text);

Step 7: (Possibly) refine the research question and return to Step 2.

From: 

https://en.wikipedia.org/wiki/Corpus-assisted_discourse_studies