Question: the nurses' health study is an example of what type of study
[{'answer': 'prospective', 'provenance': [{'wikipedia_id': '4617057', 'title': "Nurses' Health Study", 'start_paragraph_id': 1, 'start_character': 39, 'end_paragraph_id': 1, 'end_character': 50, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'long - term', 'provenance': [{'wikipedia_id': '4617057', 'title': "Nurses' Health Study", 'start_paragraph_id': 17, 'start_character': 307, 'end_paragraph_id': 17, 'end_character': 320, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'answer': 'prospective studies', 'provenance': [{'wikipedia_id': '4617057', 'title': "Nurses' Health Study", 'start_paragraph_id': 1, 'start_character': 39, 'end_paragraph_id': 1, 'end_character': 58, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': "a series of prospective studies that examine epidemiology and the long - term effects of nutrition , hormones , environment , and nurses ' work - life on health and disease development"}, {'provenance': [{'wikipedia_id': '4617057', 'title': "Nurses' Health Study", 'start_paragraph_id': 1, 'start_character': 24, 'end_paragraph_id': 1, 'end_character': 838, 'bleu_score': 0.8352525220499071, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11942048647143142166}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '4617057', 'title': "Nurses' Health Study", 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ["The Nurses Health Study is a series of prospective studies that examine epidemiology and the long-term effects of nutrition, hormones, environment, and nurses'", "The Nurses Health Study is a series of prospective studies that examine epidemiology and the long-term effects of nutrition, hormones, environment, and nurses' work-life on health and disease development. The studies have been among the largest investigations into risk factors for major chronic diseases ever conducted. The Nurses' Health Studies have led to many insights on health and well-being, including cancer prevention, cardiovascular disease, and type 2 diabetes. They have include clinicians, epidemiologists, and statisticians at the Channing Laboratory (of Brigham and Women's Hospital), Harvard Medical School, Harvard School of Public Health, and several Harvard-affiliated hospitals, including Brigham and Women's Hospital, DanaFarber Cancer Institute, Children's Hospital Boston, and Beth Israel Deaconess Medical Center.\rhighlight sentence(s) containing evidence, not only the answer", "The Nurses Health Study is a series of prospective studies that examine epidemiology and the long-term effects of nutrition, hormones, environment, and nurses' work-life on health and disease development."]}}]}]