The United States is very advanced when it comes to the study of potential jurors. In Canada, we are not there yet. The image of the law that is presented by popular culture often comes from the United States. But there are nuances when it comes to the law in Canada.
You may think that people of a certain age will be less receptive to a particular type of case, for instance, but it's often a matter of instinct. The decision is made rapidly. There is no advanced analysis or sociological study from a university sociology department that will determine that a given candidate will be more receptive. No. Normally, the lawyer listens to his instinct.
Take the example of a person who told the judge that he could without any issue perform this task, but who is looking at his feet and speaking in a very low and grumpy voice. That person may not really want to be there.