Dr. smith designs a research study in which neither the subjects nor the individuals who interact directly with the subjects know which is the control group and which is the experimental group in the study. why did dr. smith chose this type of research design?

Read the paragraph and answer the question that follows: the town of belmond, iowa, needs to add weather sirens. the loud and steady wail would warn citizens of approaching danger. if past history is an indication, the sirens will save hundreds of lives. with a prediction of a deadly storm season, the alert which sentence should be revised to eliminate redundancy? the town of belmond, iowa, needs to add weather sirens. the loud and steady wail would warn citizens of approaching danger. if past history is an indication, the sirens will save hundreds of lives. with a prediction of a deadly storm season, the alert system is needed immediately.