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. Author manuscript; available in PMC: 2011 Oct 1.
Published in final edited form as: Hear Res. 2010 Jul 16;269(1-2):48–55. doi: 10.1016/j.heares.2010.07.004

Figure 2.

Figure 2

The longitudinal changes in hearing thresholds over time by quartiles of tibia lead. The model was adjusted for baseline age, race (white or other), education (>12 yr of education or not), occupational noise (low, medium, high), time varying covariates of body mass index (kg/m2), pack-years of cigarettes (0, <30, 30+), noise notch (yes or no), diabetes and hypertension, and random intercepts and random slopes for time. The spatial exponential correlation structure was considered the covariance matrix. To capture nonlinear trajectories, linear and quadratic time terms were fit.