Which part of the united states has a mostly desert and semiarid climate

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 secretary of state, appointed by the president with the advice and consent of the senate, is the president's chief foreign affairs adviser. the secretary carries out the president's foreign policies through the state department and the foreign service of the united states.