This paper focuses exclusively on a variety of concerns relating to the protocol for assessment, effective experimental design and ultimately efficacy in research. While the efficacy and ultimate maximum worth of any research report would seem to be limited by the quality of the question posed by the practitioner, an unfavourable interaction of several factors in the research process has the potential to threaten the efficacy of the research.Within a given measurement application, there are several competing demands within the design of an experiment and its measurement protocols and that may affect the meaningful evaluation and interpretation of data. The need to limit error or increase precision of measurement to that which is commensurate with the intended application and expected extent of change or difference between performance scores may be confounded by logistical constraints. The net effect of the interaction of such demands influences the efficiency of the protocol and efficacy of the research design.Of the factors that impinge on the efficacy of the research design, those relating to precision afford the most control of measurement quality by the practitioner. Research data suggests that in many measurement applications, the error or precision associated with many indices of performance capacity that are estimated by means of single-trial protocols, is not sufficient to differentiate performance change over time in the same individual. The practitioner has available various strategies with which to dilute and counteract the adverse effects of measurement error. For example, a test protocol may incorporate the mean score of a series of performance estimates.Data interrogation can be undertaken using various strategies including formal hypothesis testing. The challenge for the practitioner is to construct an experimental design that achieves a reasonable balance between change in performance or effect size, measurement error and available sample size for a selected level of statistical significance and power. In this respect, if sufficient experimental design sensitivity can be attained then this will ensure that the practitioner can have confidence for a meaningful interpretation of the data.