Exploring data: graphs and numerical summaries

2.3 Infants with SIRDS

The data in Table 3 are the recorded birth weights of 50 infants who displayed severe idiopathic respiratory distress syndrome (SIRDS). This is a serious condition which can result in death.

Table 3 Birth weights (in kg) of infants with severe idiopathic respiratory distress syndrome

1.050* 2.500* 1.890* 1.760 2.830
1.175* 1.030* 1.940* 1.930 1.410
1.230* 1.100* 2.200* 2.015 1.715
1.310* 1.185* 2.270* 2.090 1.720
1.500* 1.225* 2.440* 2.600 2.040
1.600* 1.262* 2.560* 2.700 2.200
1.720* 1.295* 2.730* 2.950 2.400
1.750* 1.300* 1.130 3.160 2.550
1.770* 1.550* 1.575 3.400 2.570
2.275* 1.820* 1.680 3.640 3.005
*child died

(van Vliet, P.K. and Gupta, J.M. (1973) Sodium bicarbonate in idiopathic respiratory distress syndrome. Arch. Disease in Childhood, 48, 249–255.)

At first glance, there seems little that one can deduce from these data. The babies vary in weight between 1.03 kg and 3.64 kg. Notice, however, that some of the children died. Surely the important question concerns early identification of children displaying SIRDS who are at risk of dying. Do the children split into two identifiable groups? Is it possible to relate the chances of survival to birth weight?