Measurement refers to the assessment, estimation, observation, evaluation, appraisal or judgment of an event. Measurement in research (also considered a dependent variable) is the process of assigning numerals to objects to represent quantities of characteristics according to certain rules. Those involved in conducting a study must choose the most appropriate measurement scale. A study should contain one or more scales of measurement that meet the logical requirements of measurement. The least powerful measurement scale is the nominal scale, which consists of descriptive variables in no particular order. By contrast, ordinal scales have all of the requirements of nominal scales but also have the property of order. Nominal and ordinal scales usually are subject to the less powerful statistical tests such as the chi-square or the Mann–Whitney U tests. Interval and ratio scales are much more powerful than are nominal and ordinal scales because the variables provide more information about the phenomenon of interest. Parametric tests such as the t–test or AN OVA can be used for interval and ratio scales. When conducting an experiment, researchers must take steps to ensure the statistical test is reliable and valid, minimize error and biases, and use measures that are precise and accurate. Accomplishing such tasks usually requires a multidisciplinary research team but can be done by the single researcher. Orthotic and prosthetic practitioners should become more involved in this type of research, using a multidisciplinary approach, since physicians are currently less active in O&P research than they were in the past.
© 1996 American Academy of Orthotists & Prosthetists