Question

The paper “Outcomes at School Age After Postnatal Dexamethasone Therapy for Lung Disease of Prematurity”, New England Journal of Medicine, Volume 350, reports the outcomes at school age in children participating in a trial of an early postnatal therapy for preventing chronic lung disease of prematurity. All of the infants in the study had severe respiratory distress syndrome requiring mechanical ventilation shortly after birth. The attached dataset ‘Child_IQ’ contains the IQs of 74 randomly selected children from the study. Use the technology of your choice to answer the following question:

Give a 95% confidence interval for the standard deviation of IQ scores for children in the study group. ANS:  (10.8, 15.0)

IQ
88
87
70
75
75
97
83
83
89
85
92
80
91
89
79
84
66
66
77
74
81
59
81
66
85
70
68
81
88
108
82
62
57
103
83
99
84
82
99
77
111
94
77
87
84
74
74
116
96
98
88
81
68
105
96
69
81
100
109
101
96
90
94
74
81
88
84
78
70
76
99
75
92
93

Answer 1

	Values ( X )
	88	13.116
	87	6.8728
	70	206.7384
	75	87.9544
	75	87.9544
	97	159.3048
	83	1.9
	83	1.9
	89	21.3592
	85	0.3864
	92	58.0888
	80	19.1704
	91	43.8456
	89	21.3592
	79	28.9272
	84	0.1432
	66	337.7656
	66	337.7656
	77	54.4408
	74	107.7112
	81	11.4136
	59	644.0632
	81	11.4136
	66	337.7656
	85	0.3864
	70	206.7384
	68	268.252
	81	11.4136
	88	13.116
	108	557.98
	82	5.6568
	62	500.7928
	57	749.5768
	103	346.764
	83	1.9
	99	213.7912
	84	0.1432
	82	5.6568
	99	213.7912
	77	54.4408
	111	708.7096
	94	92.5752
	77	54.4408
	87	6.8728
	84	0.1432
	74	107.7112
	74	107.7112
	116	999.9256
	96	135.0616
	98	185.548
	88	13.116
	81	11.4136
	68	268.252
	105	425.2504
	96	135.0616
	69	236.4952
	81	11.4136
	100	244.0344
	109	606.2232
	101	276.2776
	96	135.0616
	90	31.6024
	94	92.5752
	74	107.7112
	81	11.4136
	88	13.116
	84	0.1432
	78	40.684
	70	206.7384
	76	70.1976
	99	213.7912
	75	87.9544
	92	58.0888
	93	74.332
Total	6244	11521.4064

Mean

Standard deviation

n = 74




Lower Limit =
Upper Limit =
95% Confidence interval is ( 116.9485 , 224.7416 )
( 116.9485 < < 224.7416 )

( 10.8 < < 15.0 )