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Medical Biomathematics and Biometrics Commons™
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Full-Text Articles in Medical Biomathematics and Biometrics
Regression Analysis In Health Services Research: The Use Of Dummy Variables, Paula Diehr, Lincoln Nayak Polissar
Regression Analysis In Health Services Research: The Use Of Dummy Variables, Paula Diehr, Lincoln Nayak Polissar
Paula Diehr
Dummy variables frequently are used in regression analysis but often in an incorrect fashion. A brief review of examples in the medical care literature showed that the interpretation of dummy variable regression coefficients and their significance was often incorrect or unclear. This article shows how dummy variables can be used and assessed properly. The importance of testing for the joint effect of a group of dummy variables is stressed. It also gives a standard and useful extension of the dummy variable technique to testing for the effect of collections of variables.
Cluster Analysis To Determine Headache Types, Paula Diehr
Cluster Analysis To Determine Headache Types, Paula Diehr
Paula Diehr
Cluster analysis was used to separate 726 headache patients into clusters of patients with similar symptoms. This was done to answer two questions: what "naturally occurring' groups of patients can be found? And how do these groups correspond to traditional headache types? When only two clusters were required, the best two clusters were tension and migraine-like. However, eight clusters could also be distinguished, and the migraine group then became very small. The clusters were tested for clinical interpretability by having 12 physicians name and prescribe treatment for the clusters. The suggested treatment was similar to what patients had actually received …