Sentence:  Methods have been developed of assigning `` weights '' to statements ; that is , it is known empirically that names beginning with R are more common than those beginning with Z ; that fewer women <WSD>are</WSD> named Miranda than Elizabeth ; that in the United States more people die of heart disease than of smallpox . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)