Moran (1974) presented data on the relationship, for Australian births, between maternal age and Down’s syndrome (a serious handicapping condition on which psychologists have done a lot of work). The data follow, though in a form that may require some minor calculations on your part to be meaningful. What can you conclude from these results?

Total Number Number of Births Age of Mother of Births With Down’s Syndrome 20 or less 35,555 15 20 –24 207,931 128 25 –29 253,450 208 30 –34 170,970 194 35 –39 86,046 197 40 – 44 24,498 240 45 or more 1,707 37 Further information on Down’s Syndrome and maternal age can be found at http://www.aafp.org/afp/20000815/825.html