Abstract
The purpose of this paper is to describe effect coding as an alternative quantitative practice for analyzing and interpreting categorical, multi-raced independent variables in higher education research. Not only may effect coding enable researchers to get closer to respondents' original intentions, it allows for more accurate analyses of all race based categories.
Notes
A key assumption underlying the approach proposed here is that the expected response of a member of multiple groups is the unweighted average of the responses of each group. It is possible that this assumption is inappropriate in a particular circumstance.
An important advantage of the proposed approach is that researchers can use it to perform a sensitivity analysis to validate the key assumption that the expected response of a member of multiple groups is the unweighted average of the responses of each group. By using dummy variables with nonzero values that differ from variable to variable to define the effect codings, researchers can fit a model with a different weighting scheme for the effect of each race on the response of a multiracial person. Varying these weights allows the researcher to see if the results are sensitive to the values of these weights. If results are not sensitive and do not change when weights are varied, we can be confident the same results will occur regardless of the weights chosen; in other words, the weights do not matter. If the results are sensitive and change when weights are added, we cannot be confident that the adoption of the unweighted average of responses of each group is the most appropriate way of effect coding for bi- and multi-raced students; this sensitivity would indicate that there may be another systematic pattern in the way bi- or multi-raced students are responding to questions about race. In this case, further analyses of these patterns would be warranted.
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Mayhew, M.J., Simonoff, J.S. Effect Coding as a Mechanism for Improving the Accuracy of Measuring Students Who Self-Identify with More than One Race. Res High Educ 56, 595–600 (2015). https://doi.org/10.1007/s11162-015-9364-0
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DOI: https://doi.org/10.1007/s11162-015-9364-0