What are the limitations of comparative juror analysis on appeal?

mindful that comparative juror analysis on a cold appellate record has inherent limitations.' [Citation.] 'One of the problems of comparative juror analysis not raised at trial is that the prosecutor generally has not provided, and was not asked to provide, an explanation for nonchallenges. When asked to engage in comparative juror analysis for the first time on appeal, a reviewing court need not, indeed, must not turn a blind eye to reasons the record discloses for not challenging other jurors even if those other jurors are similar in some respects to excused jurors.' [Citation.]" (People v. Elliott (2012) 53 Cal.4th 535, 561.)