Which writer's vision of utopia could not happen without revolution?

This problem occurs when the groups become different after the experiment begins because more participants drop out of one of the groups than out of the other(s) for various reasons.

A. selection bias B. maturation C. regression D. differential attrition

States in which different competing groups are guaranteed representation have______ democracy.

a. anarchist b. integrational c. autonomous d. consociational