What technique ensures that personal characteristics that might affect the outcome of the experiment are divided proportionally among the participants in the different groups, making groups equivalent?

In class, we discussed research on young children who were experts in particular areas. The results of this research suggest that:

a. young experts are no more sophisticated at categorization in the domain for which they are expert than are young nonexperts b. young experts tend to be very sophisticated at categorization in the domain for which they are expert, but not in other areas c. there is an advantage for young experts over young nonexperts for the biological domain (e.g., dinosaurs), but not for other domains (e.g., chess) d. children who are experts in particular areas tend to have better categorization skills across a wide range of areas, including ones far outside their area of expertise

Which statement about suicide is true?

a. all people who commit suicide are mentally ill b. suicidal behaviors run in families c. there is a proven genetic basis that causes suicidal behavior d. the familial factor of suicide is environmental