What kind of bias does this article have?
centerforreducingsuffering.org/research/intro/?gad_source=1&gclid=Cj0KCQiAoeGuBhCBARIsAGfKY7zOphVb1DwA7pBU3fM5rPLQnfKGQ6f1xM4j9dWT1sneB3JDvXgxP4YaAjJaEALw_wcB
centerforreducingsuffering.org/research/intro/?gad_source=1&gclid=Cj0KCQiAoeGuBhCBARIsAGfKY7zOphVb1DwA7pBU3fM5rPLQnfKGQ6f1xM4j9dWT1sneB3JDvXgxP4YaAjJaEALw_wcB