In 1965, in the seven states of the old confederacy covered by the voting rights act (vra), approximately percent of the eligible black residents were registered to vote, compared with approximately percent of the white residents.

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.        

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