In Exercises 1.92-1.97, we present descriptions of designed experiments. In each case, identify the

(a) experimental units

(b) response variable

(c) factor (s)

(d) levels of each factor:-

(e) treatments.

Dexamethasone and IQ. In the paper "Outcomes at School Age After Postnatal Dexamethasone Therapy for Lung Disease of Prematurity" (New England Journal of Medicine,Vol . 350, No. 13, pp . 1304-1313), T. Yeh et al . studied the outcomes at school age in children who had participated in a double-blind, placebo-controlled trial of early postnatal dexamethasone therapy for the prevention of chronic lung disease of prematurity. One result reported in the study was that, at school age, the control group of 74 children had an average IQ score of 84.4, whereas the dexamethasone group of 72 children had an average IQ score of 78.

The given statement is:

In the paper "Outcomes at School Age After Postnatal Dexamethasone Therapy for Lung Disease of Prematurity", T. Yeh et al . studied the outcomes at school age in children who had participated in a double-blind, placebo-controlled trial of early postnatal dexamethasone therapy for the prevention of chronic lung disease of prematurity. One result reported in the study was that, at school age, the control group of 74 children had an average IQ score of 84.4, whereas the dexamethasone group of 72 children had an average IQ score of 78.

Taking into consideration the given designed experiment, the Experimental units are the children that are being studied for the prevention of chronic lung disease of prematurity.

The response variable, of the given designed experiment, is the IQ score.

Because the IQ of different school children is being measured here.

Here, the factors include:

Whether the children belong to the group to whom dexamethasone therapy was given or not.

Here, the levels of each factor include:

The control group and dexamethasone group.

It includes the control group and dexamethasone group.