Using Section 3.10 as a guide, perform the following analyses. (a) Fit a threshold model to the sunspots series displayed in Figure 1.1. (b) For the mortality series, say M t , shown at the bottom of...

Using Section 3.10 as a guide, perform the following analyses.

(a) Fit a threshold model to the sunspots series displayed in Figure 1.1.

(b) For the mortality series, say M_t, shown at the bottom of Figure 3.1, calculate the normalized bispectrum of the series itself and then of X_t
= ∇lnM_t. What is the interpretation of Xt? Comment on the difference between the results. Then, fit a threshold model to X_t. Explain why it is better to fit such a model to X_t
rather than M_t.

(c) Fit a GARCH (or GARCH-type) model to the explosion series in Figure 3.6 and comment.

(d) Analyze the great discoveries and innovations series displayed in Figure 3.7