About: http://webisa.webdatacommons.org/285303216

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Large samples are often required making studies relatively expensive, particularly if the outcome is rare or coupled with a long follow-up period in the case of prospective studies.
http://www.w3.org/ns/prov#wasQuotedFrom	dot.gov