What does it mean when an observational study is retrospective

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.

citizens were able to charge more for their goods and services

answer; ratification;