Blood pressure values are often reported to the nearest 5 mmHg (100, 105, 110, e
ID: 3273827 • Letter: B
Question
Blood pressure values are often reported to the nearest 5 mmHg (100, 105, 110, etc.). The actual blood pressure values for nine randomly selected individuals are given below. 118.6 127.4 138.4 130.0 113.7 122.0 108.3 131.5 133.2 (a) What is the median of the reported blood pressure values? _________ mmHg (b) Suppose the blood pressure of the second individual is 127.6 rather than 127.4 (a small change in a single value). What is the new median of the reported values? __________ mmHg What does this say about the sensitivity of the median to rounding or grouping in the data? When there is rounding or grouping, the median can be highly sensitive to small change. When there is rounding or grouping, the median is only sensitive to large changes. When there is rounding or grouping, the median is not sensitive to small changes.Explanation / Answer
(a) Arranging data in ascending order, we get: 108.3, 113.7,118.6,122.0,127.4,130.0,131.5,133.2,138.4
Median = 127.4
n = 9
Median = 5th item = 127.4
(b) If 127.4 is changed to 127.6,
new median = 127.6
(c) Correct option:
When there is rounding or grouping, the median can be highly sensitive to small changes.