Nursing research is the systematic collection and analysis of data about clinically important phenomena. While there are norms for conducting research and rules for using certain research procedures, the reader must always filter the research report against his or her nursing knowledge. The most common questions a reader should ask are "Does it make sense? Can I think of any other reasonable explanation for the findings? Do the findings fit what I have observed?" If the answers are reasonable, research findings from carefully conducted studies can provide a basis for making nursing decisions. One of the earliest accounts of nursing research, which indicates the power of making systematic observations, was Florence Nightingale's study. It compared deaths among soldiers in the Crimean War with deaths of soldiers in the barracks of London. Her research demonstrated that soldiers in the barracks had a much higher death rate than did the soldiers at war. On the basis of the study, sanitary conditions in the barracks were changed substantially.