Recent research into the validity of oral language interviews has extended the focus beyond that of statistical analysis to investigations of the structure of the interview discourse itself, and to the language produced by both candidate and interviewer. Research has indicated that, despite training, interviewer behaviour varies considerably in terms of the amount of support they give candidates, the amount of rapport raters consider them to have established with candidates and the extent to which they follow the instructions in terms of the type of discourse elicited from candidates. While several writers allude to the potential of such variable interviewer behaviour to affect the validity of tests, studies have not yet empirically investigated the relationship between interviewer behaviour and candidate performance.
The study aims firstly to investigate the extent to which differential behaviour by IELTS interviewers affects the scores awarded to candidates and to identify interviewers who consistently present a difficult or easy challenge to candidates. The second part of the study involves a discourse analysis of the contributions of 'difficult' and 'easy' interviewers, and aims to identify aspects of interviewer behaviour which contribute to the challenge they present.
The study is based on interviews undertaken with 32 candidates, each of whom was interviewed twice by two different interviewers. Six interviewers took part in the study. The interviews were audio-taped and multiple-rated.