Legal precedent states that in the event there is 'any reasonable doubt' that the defendant will have the benefit of an impartial jury, a change of venue should be granted. Judicial discretion determines when such a reasonable doubt exists. What should be of major concern in a change-of-venue hearing is whether the prospective jurors have one-sided predispositions as to the guilt of a defendant prior to the presentation of evidence. In cases where there is no systematic evidence as to the nature and extent of predispositions in a given locality, the quantity of pretrial publicity becomes a major concern, since it indicates the likelihood that such predispositions exist. The pretrial circulation of inadmissible evidence can also prejudice prospective jurors. Overall, while it may appear that the voir dire (prospective juror questioning and selection) may in some circumstances help to combat the influence of inadmissible evidence, it is not by itself an adequate safeguard. Another evidence of prospective-juror impartiality is the presence in a significant percentage of citizens of the trial locality of a prejudgment of criminal tendencies in certain racial, ethnic, or subcultural groups of which the defendant may be a representative. A scientific assessment of impartiality through a sociological survey can provide empirical evidence of prospective-juror prejudice, but the judge must finally determine whether evidence of prospective-juror impartiality is sufficient to create a resonable doubt about a defendant's receiving a fair trial in the jurisdiction of the crime. Scientific evidence showing a predisposition of guilt in 35 percent of the population should be sufficient evidence for a change of venue.