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Next: Conclusions Up: Coalescence Previous: Evaluation of Posterior

 

Results

The kernel density estimates for the marginal distribution of the various parameters may be of interest, but as far as model checking is concerned, the procedure adopted was to censor the final datapoint and make predictions based on the rest of the data.

That is;

eqnarray1091

And so we use the posterior predictive distribution in order to estimate the value of tex2html_wrap_inline3103 . Quite favourable results are achieved, as outlined in the Figure gif.

  figure1100
Figure: KDE of D[6] for 200kN Data.  

The figure shows the posterior kernel density estimate for tex2html_wrap_inline3153 conditional on tex2html_wrap_inline3155 . The actual observed value for tex2html_wrap_inline3153 was 35. The mean of the kernel density was 33.4 and the median was 34. This analysis was for the 200kN data. Similar results were obtained for the 140kN and 160kN sets and are included in Figure gif and Figure gif.

  figure1109
Figure: KDE of D for 140kN data.  

The actual observed number of coalescences for the 140kN Data was 7. The mean and median from the kernel density estimate were 5.4 and 4 respectively.

  figure1116
Figure: KDE of D for 160kN data.  

The actual observed number of coalescences for the 160kN Data was 28. The mean and median from the kernel density estimate are 33.2 and 34 respectively. In all these cases the observed value falls comfortably within the 25th and 75th percentiles of the kernel density estimate.

For completeness, the trace for tex2html_wrap_inline3163 for the 140kN chain is included in Figure gif. The chains were similar for the other parameters of interest.

  figure1124
Figure: Chain for tex2html_wrap_inline3163 for 140kN Data.  

Thus, a straightforward model is employed in the modelling of rate, and it appears to fit the data which we have. Concern should be expressed about a number of the details; this is done in what follows. However, even this simple model allows a very important insight.


next up previous contents
Next: Conclusions Up: Coalescence Previous: Evaluation of Posterior

Cathal Walsh
Sat Jan 22 17:09:53 GMT 2000