1. A study was conducted after 55 years to find radiation dose response relationships for thyroid nodules and autoimmune thyroid disease in Hiroshima and Nagasaki atomic bomb survivors after radiation exposure. Among 2739 female atom bomb survivors, 1397 developed thyroid diseases. Among 1352 male atom bomb survivors, 436 developed thyroid diseases. Use a 0.01 significance level to test the claim that the female survivors and male survivors have different rates of thyroid diseases.