Dr. Spock is trying to determine what traits, if any, high-achieving students have that students who do poorly on his exams do not possess. To assess personal information from both groups of students, what research method should Dr. Spock probably use?

european feudalism was a combination of legal and military customs in medieval europe that flourished between the 9th and 15th centuries. broadly defined, it was a way of structuring society around relationships derived from the holding of land in exchange for service or labour.

japanese feudalism. the era of feudalism in japan took place from the 12th through 19th centuries. during that period local rulers, either powerful families or military warlords, dominated the land, while the emperor was merely a figurehead and not a significant political presence.

answer; the intervening variable;