This paper was published online on 5 November 2010 and appeared in the November-December 2010 issue of the journal (Vol. 21, No. 7-8, pp. 789–800).
Subsequent to publication we would like to make the following correction to the affiliation:
Jiguo Cao's affiliation should be “bDepartment of Statistics and Actuarial Science; Simon Fraser University; Burnaby, Canada V5A 1S6”