a data.frame where each row contains the results of a cosinor test
performed on the corresponding row/column of x.
Each row contains the following information (in order):
1. obs - total number of observations
2. mesor - "Midline Estimating Statistic Of Rhythm" - the average value around which the variable oscillates
3. amplitude - difference between mesor and the peak of the rhythm
4. acrophase - time when rhythm reaches its peak
5. rsquared - R-squared
6. df.model - model terms degrees of freedom
7. df.residual - residual degrees of freedom
8. statistic - F statistic for the omnibus test against intercept-only model
9. pvalue - p-value
10. period - the period used within the model