The Zenger-Cosby trial in Colonial New York had what effects

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.        

the answer to your question is,

d. when a child was born.

-mabel < 3

answer; /// the above is ( false );

answer; ( correlation );