Statistical Data Analysis
The recorded data for heart rate, systolic blood pressure, and diastolic blood pressure for
all 150 subjects was analyzed using an excel spreadsheet. The average or mean for all three
variables was calculated. The average percent difference between resting heart rate and heart rate
after each of the exercises (15 steps and 30 steps), and the average percent difference between
systolic and diastolic blood pressures at rest and after exercise was also calculated.
The standard deviation of the average values and difference in average values for the
control and pre-treatment groups was calculated in addition to the standard error. The averages
and standard deviation were used in an effort to find the p-value. The p-values for each variable
illustrated the probability that changes in heart rate and arterial blood pressure levels were due to
caffeine consumption. The p-value is based on the null hypothesis (i.e. there is not a statistical
significance/difference between the control group and pre-treatment group) (4). Therefore, a
lower p-value suggests a difference between the two groups due to caffeine consumption, while a
high p-value illustrates that any effect that caffeine has on heart rate or arterial blood pressure is
due to random chance (4). A p-value of equal or lesser value to 0.05 demonstrates statistical
significance. A p-value higher than 0.05 suggests that the null hypothesis is true and there is no
difference between the control group and pre-treatment group (i.e. any changes in the three
variables is not due to caffeine consumption but rather random chance).
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Results
Table 1
: Average Resting Values of Heart Rate, Systolic Blood Pressure, and Diastolic Blood
Pressure
Average Resting Values of Heart Rate, Systolic Blood Pressure, and Diastolic Blood Pressure:
The mean of each the pulse count, systolic blood pressure, and diastolic blood pressure at rest is
given by the average. SD= standard deviation, SE= standard error of the mean, the standard error
of the mean was calculated using the following equation: (SD/ square root of sample size n)
Pulse count
Sys.BP
Dias.BP
0
20
40
60
80
100
120
140
Average Resting Values
Control
Pre-Treatment
Variable
Average
Figure 1. Average Resting Values: Graphical Presentation of the data shown in Table 1. The bar
graph shows the average resting values for the three variables tested (pulse count, SBP, and
DBP) for control and pre-treatment groups. Error bars represent the standard error of the mean
for each variable (see table 1 for values). The asterisk (*) above the average resting values for
systolic blood pressures indicates that statistical significance was found.
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