Original: He was the first to apply statistical methods to the study of human differences and inheritance of intelligence, and introduced the use of questionnaires and surveys for collecting data on human communities, which he needed for genealogical and biographical works and for his anthropometric studies.
Simplified: He was the first to apply statistical methods to the study of human differences and inheritance of intelligence. He also introduced the use of questionnaires and surveys to collect data on human communities. He needed such data for genealogical and biographical works and for his anthropometric studies.