The Shanghai Women’s Health Study (SWHS) was under-taken to determine risk factor for different cancers among Asian women. The women were recruited from urban communities in XXXXXXXXXXand were...

The Shanghai Women’s Health Study (SWHS) was under-taken to determine risk factor for different cancers among Asian women. The women were recruited from urban communities in 1997-2000 and were interviewed every 2 years to obtain health-related information. One issue is whether risk prediction models derived from American populations are also applicable to Asian women. Suppose the expected number of breast cancer cases among a large number of 45-to 49-year-old women in this study who were followed for 7 years is 149, while the observed number of cases is 117. Are there an unusual small number of cases among Asian women? Why or Why not?