1.An instrument that is frequently used for taking blood-pressure readings is the random-zero device, in which the zero point of the machine is randomly set with each use and the observer is not aware of the actual level of blood pressure at the time of measurement. This instrument is intended to reduce observer bias. Before using such a machine, it is important to check that readings are comparable to those of a standard cuff. For this purpose, two measurements were made on 20 children with both the standard cuff and the random-zero machine. The systolic blood pressure (SBP) readings for the 20 children from the two machines are given in the table below. Use these data to answer the questions below the table.

Child

SBP (mm Hg)

(standard cuff)

SBP (mm Hg)

(random-zero)

1

79

84

2

112

99

3

103

92

4

104

103

5

94

94

6

106

106

7

103

97

8

97

108

9

88

77

10

113

94

11

98

97

12

103

103

13

105

107

14

117

120

15

94

94

16

88

87

17

101

97

18

98

93

19

91

87

20

105

104

a.Createonefigure that shows the differences in SBP readings for the two methods for each child. Does there appear to be a consistent pattern across the 20 children?

b.Suppose researchers are reluctant to assume that the distribution of SBP readings is normally distributed. Conduct the appropriate statistical test to determine whether the blood pressure readings from the two machines are comparable. What do you conclude? Assume a 0.05 level of significance.