¶ … calculates the 95% confidence intervals of two data sets, one for the reading of systolic blood pressure and one for the reading of diastolic blood pressure. There was a sample size of 9 total patients included. The steps of reaching the confidence interval are outlined below. Excel was used to find the mean for each data set as well as the standard deviation using the formula provided. From there, the steps were manually calculated.

The confidence interval must be calculated through a number of steps. Some of these were done on excel, while others had to be calculated manually. The first step was to find the average of the data set for each type of blood pressure measured. The systolic average was 131.1 repeating, while the diastolic mean was 75.5 repeating. Next, standard deviation was found using the following formula:

The standard deviation for systolic blood pressure was 23.15407332, while it was 20.68278941 for diastolic blood pressure. The next step was to compute the standard error, which was done by dividing the standard deviation by the square root of the sample size. For systolic blood pressure that meant dividing 23.15407332 by 3, which meant the standard error was 7.7180244. For diastolic blood pressure, the formula was as follows: 20.68278941 / 3, or 6.8942631367. Next, the margin of error was calculated by multiplying the standard error by two. For systolic blood pressure, that meant a margin of error of 15.4360488 and for diastolic a margin of error of 13.7885262734. Finally, the confidence interval was calculated by adding and subtracting the margin of error to the mean of each of the two data categories. This would give the range of the 95% confidence interval for the two blood pressure measurements. For systolic blood pressure (131.11111+15.4360488 and 131.11111-15.4360488), the 95% confidence interval falls between 115.6750512 and 146.5471598. For diastolic (75.56+13.7885262734 and 75.56-13.7885262734), this meant the confidence interval was between 61.7714737266 and 89.3485262734.

Patient

Systolic

Diastolic

1

2

90

3

60

4

80

5

70

6

90

7

80

8

60

9

90

40

Mean

75.

Standard Deviation

23.15407332

20.68278941

Standard Error

7.7180244

6.894263137

Margin of Error

15.4360488

13.78852627

Confidence Interval

115.6750512 and 146.5471598

61.7714737266 and 89.3485262734