Down’s syndrome is another problem that psychologists deal with. It has been proposed that mothers who give birth at older ages are more likely to have a child with Down’s syndrome.

Plot the data below relating age to incidence. The data were taken from Geyer (1991).

Age 17.5 18.5 19.5 20.5 21.5 22.5 23.5 24.5 25.5 Births 13,555 13,675 18,752 22,005 23,796 24,667 24,807 23,986 22,860 Downs 16 15 16 22 16 12 17 22 15 Age 26.5 27.5 28.5 29.5 30.5 31.5 32.5 33.5 34.5 Births 21,450 19,202 17,450 15,685 13,954 11,987 10,983 9,825 8,483 Downs 15 27 14 9 12 12 18 13 11 Age 35.5 36.5 37.5 38.5 39.5 40.5 41.5 42.5 43.5 Births 7,448 6,628 5,780 4,834 3,961 2,952 2,276 1,589 1,018 Downs 23 13 17 15 30 31 33 20 16 Age 44.5 45.5 46.5 Births 596 327 249 Downs 22 11 7 Plot a scatter diagram for the percentage of Down’s syndrome cases (Down’s/Births) as a function of age.