Jim, a researcher, attempts to test the effect of the environment in an examination hall on a student's performance. However, he gives students question papers that differ in complexity and subject matter. His results would not be reliable because the complexity and subject matter of the examination are.

What policy did "jim crow" laws put in place? black codes integration segregation 2. the supreme court case that established the doctrine of "separate but equal" was dred scott v. sandford plessy v. ferguson brown v. board of education 3. the supreme court case that overturned the doctrine of "separate but equal" wasdred scott v. sandford plessy v. ferguson brown v. board of education

According to bowers, which of the following best describes the dominance of interest groups in the state of nevada over time? political machines dominated during the first 50 years; from 1908 to 1958 railroad and mining interests dominated; primarily gaming interests from 1958 to the present. the railroad and mining interests dominated during the first 50 years of statehood; political machines dominated from 1908 to 1958; primarily gaming interests have dominated from 1958 to present. gaming interests have always dominated. railroad and mining interests dominated from statehood until 1959; gaming interests have dominated from 1959 to present. no one interest has ever dominated at any one time.

The form the boundary between north and south china. a. himalayan mountains c. change river b. xi river d. qinling shandi mountains