Fig. 4.

Visualization of the near-transyear component detected linearly in Fig. 3 for the quarterly percentage change in new cases of autism in California, compared with the anticipated circannual variation. The data have been stacked over idealized cycles with a period of either 1.09 (top) or 1.00 (bottom) year. The absence of a yearly pattern and instead the presence of a half-yearly pattern is clearly apparent, more cases being reported in the spring and autumn than in the summer and winter (bottom). This impression is validated by one-way analysis of variance, using two classes anticipating a 6-month component (P = 0.031). The fit of a precise yearly component is not statistically significant (see dotted line at bottom). By contrast, the continuous line on top, corresponding to the neartransyear, shows a smooth pattern, further validated by cosinor on the timepoint means (P = 0.027). © Halberg.