Năm 1970, tỷ lệ chết thô của Guyana (một nước chậm phát triển ở Nam Mỹ) là 6,8/ 1 000, và của Hoa Kỳ là 9,6/ 1 000.  Người ta giải thích rằng, tỷ lệ đó của hoa Kỳ cao hơn Guyana vì:

Trong định nghĩa về dịch tễ học, "dịch" được xác định khi có sự gia tăng đáng kể về số lượng ca bệnh so với mức bình thường được ghi nhận tại một địa phương cụ thể trong một khoảng thời gian ngắn. Do đó, từ thích hợp nhất để điền vào chỗ trống là "Tỷ lệ", vì nó thể hiện sự so sánh số lượng ca bệnh thực tế so với số lượng dự kiến hoặc trung bình. Các lựa chọn khác không phù hợp vì "Số" chỉ đơn thuần là số lượng, "Tần số" đề cập đến số lần xuất hiện, và "Tỷ số" là một khái niệm toán học khác.

Câu hỏi đề cập đến trường hợp kết quả xét nghiệm chưa đủ để đưa ra quyết định điều trị. Điều này thường xảy ra với các test phát hiện bệnh (screening test) hoặc test có độ nhạy cao. Các test này thường được sử dụng để sàng lọc ban đầu và cần được xác nhận bằng các test chẩn đoán có độ đặc hiệu cao hơn trước khi tiến hành điều trị. Trong các lựa chọn đưa ra, "Test phát hiện bệnh" phù hợp nhất vì nó chỉ ra rằng cần có các xét nghiệm khác (thường là test chẩn đoán) để xác nhận trước khi điều trị.

Nghiên cứu dịch tễ học phân tích được sử dụng để kiểm tra các giả thuyết về mối quan hệ nhân quả giữa các yếu tố nguy cơ và bệnh tật. Nghiên cứu mô tả chỉ đơn thuần mô tả sự phân bố bệnh tật, trong khi nghiên cứu thực nghiệm can thiệp để thay đổi một yếu tố và quan sát kết quả. Nghiên cứu tương lai không phải là một loại nghiên cứu dịch tễ học cụ thể, mà là một hướng tiếp cận (ví dụ, nghiên cứu кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого кого 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Tình trạng hôn nhân có ảnh hưởng đến sức khỏe thể chất và tinh thần của một người. Các nghiên cứu cho thấy những người ở vậy, góa bụa hoặc ly dị thường có tỷ lệ tử vong cao hơn so với những người có vợ/chồng. Trong các lựa chọn được đưa ra, những người góa bụa thường phải đối mặt với nhiều căng thẳng và cô đơn sau khi mất đi người bạn đời, điều này có thể ảnh hưởng tiêu cực đến sức khỏe và làm tăng nguy cơ tử vong.