Logistic Regression: Psychiatric Screening, Plasma Proteins, Danish Do-It-Yourself and Lower Back Pain
The second data set, part of which is given in Table 8.2, was collected to examine the extent to which erythrocyte sedimentation rate (ESR), that is, the rate at which red blood cells (erythrocytes) settle out of suspension in blood plasma, is related to two plasma proteins, fibrinogen and g-globulin, both measured in g=L (Collett, 2003a). The ESR for a ‘‘healthy’’ individual should be less than 20 mm=h, and since the absolute value of ESR is relatively unimportant, the response variable used here denotes whether or not is less than 20mm=h. A response of zero signifies a healthy individual (ESR< 20) while a response of one refers to an unhealthy individual
(ESR 20). The aim of the analysis for these data is to determine the strength of any relationship between the ESR level and the levels of the two plasmas.