The study used both quantitative methods (questionnaire,
classroom observation checklists) and a qualitative method
(interview) for data gathering. The combination of methods was
designed to give reliable measures of changes in teacher behaviours,
to validate this data through triangulation and to give a richer or
more detailed account of the participants’ understandings and
attitudes during the process of changes. The researcher acted both
as the manager of the PDP (controlling input through seminars,
viewing and helping to assess videotapes of teachers in their
classrooms, discussing pedagogical issues with supervisors and
teachers after lessons) and as researcher (devising data-gathering
instruments, recording interviews, organising and analysing data,
evaluating the programme from the data gathered). Bias that could
be introduced through this duplication of role has been minimised
wherever possible, especially in giving the key responsibility for
rating teacher behaviour to their supervisors, keeping permanent
records (videotaping lessons and tape recording interviews), using
independent translators to check accuracy of Thai/English
translation of data, and the use of multiple research methods and
instruments for gathering data.