Specifically with regard to research on professional coaching, if we don’t use a multi-source/multi-method approach then we don’t know if we are generating unbiased information from our single source (coach, client or supervisor) and we don’t know if we are obtaining information about the impact of our single measurement tool on the people we are studying or are obtaining information about the people themselves and the coaching process. For instances, if we only conduct interviews then we might be discovering something about the fear factor: how much do the subjects of our study want to reveal about what is really happening in the coaching process? A study about organizational fear is important, but it doesn’t tell us much about what is really happening in the coaching sessions. Similarly, a questionnaire when used exclusively, may tell us quite a bit about the way respondents assess the coaching process when given a chance to rate the process using categories and criteria formulated by someone else, but these results tell us very little about how the coach or client actually perceive the coaching engagement (using their own criteria) or about the actual experience of the coach or client (using their own categories). A so-called “phenomenological” perspective cannot be gained from the use of questionnaires, just as generalized conclusions can rarely be generated from the exclusive use of interviews.

While a multi-method study can be logistically challenging, numerous methods are available to those conducting research about coaching. I propose that at least ten different methods for collecting information are available to most coaching researchers: (1) interviews, (2) observation, (3) participant-observation, (4) archival (document) review, (5) unobtrusive measurement, (6) obtrusive measurement (participant-observation of reactivity), (7) performance reviews, (8) questionnaires, (9) critical incident checklists and (10) general information about comparable problems and programs. A researcher is limited only by time and creativity in her use of these information collection tools.