Figure 3

Multiple-component single cosinor. Systolic blood pressure data collected over 7 days by a 45-year old woman fitted with a 24-hour cosine curve indicate the presence of lack of fit, departure from normality of residuals, and inhomogeneity of variance (left). The addition of a 12-hour component (middle) to the model (right) yields a better fit for which underlying assumptions are validated. © Halberg Chronobiology Center.