The effect of blood donation frequency and gender on physiological response to blood loss
Stephanie Melton and Jessica Ochoa
Department of Biological Science
Saddleback College
Mission Viejo, CA 92692
The human body has several physiological compensation mechanisms for blood loss. A change in
blood pressure is one such mechanism. A blood donor loses approximately ten percent of total
blood volume when donating blood. Ten percent is a blood volume significant enough to stimulate
compensation mechanisms. This study was conducted to test the hypothesis that there is a
significant difference between the pre- and post-donation blood pressures in first-time donors,
compared to frequent donors. The objective of the study was to evaluate if donors physiologically
adapt to blood loss if blood loss occurred frequently. The study took pre- and post-blood donation
blood pressures from thirty frequent donors and thirty first-time donors. Our results indicate that
there is not a significant difference in the change in systolic and diastolic blood pressures pre- and
post- donation in frequent donors compared to first-time donors. (unpaired t-test, two-tailed,
p>0.05) These results suggest that frequent donors do not adapt to blood loss. Also within this
study frequent male donors were compared to frequent female donors and first time male donors
were compared to first time female donors. The study found that there was no significant difference
in the body’s physiological response that correlates to gender.
Introduction
The human body contains, on average, five pints of blood (Velasquez, 1987). Blood is an essential bodily fluid
that is comprised of hematocrit, or red blood cells, and plasma. The red blood cells contain the hemoglobin protein
that carries oxygen to organs and muscles and aids in the removal of carbon dioxide. Each hemoglobin contains a
heme groups, to which iron binds. This iron is the binding site for oxygen (Franchini, 2008). The circulation of
blood throughout the body is maintained by heart rate, cardiac output, and blood pressure. Cardiac output and blood
pressure are monitored by baroreceptors in the aortic arch and carotid arteries. Baroreceptors detect the amount and
the pressure of blood passing through the aorta and carotid arteries during each heart beat (Mancia, 1986).
Baroreceptors are also responsible for moderating heart rate in response to changes in blood pressure (Parati, 218).
Whole blood donation involves the removal of 500 mL of blood (hematocrit and plasma) from the donor. This
volume corresponds to a reduction of approximately 10 percent of total blood volume (Velasquez, 1987). With the
loss of hematocrit, approximately 225-250 mg of heme is removed (Salonen, 446). Consequently, the concentration
of oxygen in the body is reduced (Meyers, 1997). The loss of oxygen, if severe enough, will decrease tissue
perfusion, which will eventually lead to cellular hypoxia, organ damage, and death (Peng, 2005).
When a subject loses blood (hemorrhage), the body initiates several neurohumoral compensation feedback
mechanisms. Some mechanisms are immediate; others are slow-acting, long-term mechanisms (Haberthur, 2003).
The volume of blood lost directly corresponds to the severity of the compensation. During a minor amount of blood
loss, physiological compensation is not noticeable. However, when blood loss is around 10 percent, such as with
blood donation, several compensatory mechanisms occur in the body.
The immediate mechanisms are initiated by the baroreceptors. When the baroreceptors in the aortic arch and
carotid arteries detect a reduced blood volume, signals are sent from the sympathetic nervous system causing heart
rate to increase, arteriole beds in muscle and skin to constrict, and veins to constrict (McGuill, 1989). The
combination of these three responses is effective in the maintenance of arterial pressure, venous return to the heart,
and cardiac output (McGuill, 1989). This ensures organs and tissues remain adequately perfused. With a blood loss
volume greater than 10 percent, a subject would suffer significant decrease in blood pressure and cardiac output, as
well as tachycardia, and further arteriolar constriction (McGuill, 1989).
The long term mechanisms function to replace the lost blood volume. These responses include the secretion of
antidiruetic hormone and the activation of renin-angiotensin aldosterone hormone system (McGuill, 1989). These
hormones function in the kidneys to reduce the amount of fluid lost in urine through the re-absorption of fluids.
This re-absorption of fluid increases blood pressure by increasing the volume of fluid in the body (McGuill, 1989).
Another long-term response is the release of erythropoietin by the kidneys to stimulate the production of new
red blood cells (Salonen, 1998). Approximately eight weeks recovery time is required between blood donations.
This recovery time allows the blood volume that was removed to be replenished by the production of new red blood
cells.
Several studies have been conducted to evaluate the effect of acute blood loss on blood pressure and mean
arterial pressure (MAP). (What exactly is MAP?)One study found that acute loss of blood resulted in a slight
decrease in systolic blood pressure and no change in diastolic blood pressure post blood donation in hypertensive
subjects (Velasquez, 1987). A separate study found that hemorrhage resulted in a sympathetic nervous system
response (i.e., increase heart rate and blood pressure) (Haberthur, 2003).
This study was conducted to evaluate the effects of blood loss on systolic and diastolic blood pressure, heart
rate, and mean arterial pressure. Whole blood donors were the participants. The purpose of the study was to
determine if people physiologically adapt to blood loss if the body is subjected to the stress of hemorrhage
frequently. Such adaptations would include a lessened increase in heart rate, less arteriolar and venous constriction,
and a lessened increase in blood pressure. This study focused on changes in pre- and post-donation systolic and
diastolic blood pressures, heart rate, and MAP. The hypothesis being tested is that there is a significant difference
between the pre- and post-donation blood pressures, heart rate, and MAP in first-time donors compared to frequent
donors.
Materials and Methods
The study subjects consisted of blood donors at various American Red Cross donation centers throughout
Orange County, California. The subjects were divided into two groups depending on the frequency of blood
donation. Frequent donors were classified as donors who donate blood three or more times a year. First-time
donors were donors who had not previously donated blood. The subjects were further divided into two based on
sex, male and female. The two data groups consisted of frequent donors and first-time donors. Other variables
affecting heart health were not taken into consideration. Since the only factor being evaluated is the change in blood
pressure, heart rate, and mean arterial pressure due to blood loss, any extraneous health conditions were not
considered to significantly influence the data. The data groups consisted of 30 first time donors and 30 frequent
donors. Of these, half were male and half were female. Overall the prediction was there would be a reduced change
in the pre- and post-donation for frequent donors compared to first-time donors. Specifically, it was predicted that
frequent donors would have a smaller decrease in blood pressure than first time donors. The change in heart rate
was predicted to smaller in frequent donors than first time donors. The drop expected in mean arterial pressure was
predicted to be less in frequent donors than first time donors.
Data were collected from October 15, 2009 to November 6, 2009. Each donor was asked the frequency of
blood donation to categorize the subject in the correct data group. The sex of the donor was also recorded. Using a
sphygmomanometer and stethoscope, the subject’s blood pressures were taken auscultatively before and after
donating blood. Heart rate was palpated at the wrist before and after donation as well. Mean arterial pressure was
calculated from the blood pressures using the equation: MAP=[(2D)+S]/3, where D equals diastolic blood pressure
and S equals systolic blood pressure.
Where D equals diastolic blood pressure and S equals systolic blood pressure. (You could probably leave it as you
had it, but I think this looks a bit sharper)
The collected data were statistically analyzed using Excel software (Microsoft Corporation, Redmond,
Washington) to determine if there was a significant difference in pre- and post- donation systolic and diastolic blood
pressures, heart rate, and mean arterial pressures between the first time donors and frequent donors and between
males and females. The first statistical test, a paired F-test with variances, was used to determine if there were
unequal variances between the data groups. The F-test was followed with a two-tailed, unpaired T-test. The T-test
was used to determine if a significant difference exists between the pre- and post-donation systolic and diastolic
blood pressures, heart rate, and mean arterial pressure of frequent and first-time blood donors. T-tests will also be
performed to determine if there is a significant difference between males and females for all data collected. (Delete
space between p and parenthesis) ( p<0.05 will be considered as significant.)
Results
The results of the statistical analysis indicated that there was not a significant difference between blood
pressure, heart rate, and MAP of frequent donors and first time donors and between males and females. For frequent
donors, the mean change in systolic blood pressure was a drop of 1.7 mmHg (sd=6.2). The mean change in diastolic
blood pressure was a drop of 0.8 mmHg (sd=6.6). For first-time donors, the mean change in systolic blood pressure
was a drop of 2.3 mmHg (sd=7.8). The mean diastolic blood pressure change was a drop of 3.4 mmHG (sd=10.2).
Each group had a sample size of 11 donors. The mean change in heart rate for frequent donors was an increase in
2.6 BPM (sd=10.8). For first time donors, the mean change in heart rate was an increase in 3.4 BPM (sd=8.4). The
change in average MAP for frequent donors was a drop of 1.2 mmHG (sd=5.5) and for first time donors was a drop
in 3.0 mmHG (sd=7.7).
The average change in male systolic blood pressure for frequent donors was a drop of 1.1 mmHG (sd=4.6). For
first time donors, the average drop in systolic blood pressure was 2.5 mmHG (sd=8.2). For frequent female donors,
the drop in mean drop in blood pressure was 2.7 mmHG (sd=7.6); first time female donors experienced an average
drop of 2.0 mmHG (sd=7.8). Male frequent donors and first time donors experienced a drop in diastolic pressure of
1.1 mmHG (sd=8.2) and 5.3 mmHG (sd=11.4), respectively. Females, experienced a drop of 0.5mmHG (sd=5.0)
for frequent donors and 1.4 mmHG (sd=8.3) for first time donors. Males who donated frequently had an average
decrease in heart rate of 0.2 BPM (sd=13.2). First time male donors had an increase of 1.5 BPM (sd=6.3). For
female donors, those who donated frequently experienced an average increase of 4.9 BPM (sd=7.0). First time
donors had an average increase of 5.9 BPM (sd=6.3) Mean arterial pressure dropped for frequent male donors by
1.06 mmHG (sd=6.4). The drop for first time male donors was 4.36 mmHG (sd=9.0). For female frequent donors,
the drop in MAP was 1.28 mmHG (sd=4.60). The drop for first time donor was 1.58 mmHG (sd=6.34).
(I know you are doing a F-test, a test in differences of standard deviation, but do you have to report SEM and
N=# along with the mean; since you are also doing a T-test)
The results of the F-test indicated that there were unequal variances between frequent and first time donors for
all parameters evaluated except the change in diastolic blood pressure for frequent and first time donors, the change
in systolic blood pressure in males, and the change in heart rate in male donors, and the change in heart rate for
frequent donors between males and females (p<0.05) What was the actual P-value?.
The results of the two-tailed, unpaired T-test indicated that there was not a significant difference between preand post donation systolic pressures between frequent and first time donors, (T-test assuming unequal variances,
t=0.26, df=40, and p>0.05) (Figure 1). The data also indicated that there was not a significant difference in the preand post-donation diastolic pressures (T-test assuming equal variances, t=0.98, df=37, and p>0.05) (Figure
2). (Consistency – In your figures your results are to the hundredth place; while in the results portion they are to the
tens place.)
Your Y-axis label is also difficult to read
Mean Change in Systolic Blood
Pressure (mmHg)
-4.50
-4.00
-3.50
-3.00
-2.50
-2.00
-1.50
-1.00
-0.50
0.00
Frequent
First Time
Frequency of Donation
Figure 1. Mean change in systolic blood pressure versus frequency of donation. The mean change in systolic blood
pressure for frequent donors was a drop of 1.73±1.3 mmHG (±SEM), N=11. The mean change in systolic blood
pressure for first-time donors was a drop of 2.27±1.7 mmHG (±SEM), N=11. Mean change in systolic blood
pressure was not significantly different between frequent and first-time donors (p>0.05, two-tailed, unpaired t-test).
Mean Change in Diastolic Blood
Pressure (mmHg)
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
Frequent
First Time
Frequency of Donation
Figure 2. Mean change in diastolic blood pressure versus frequency of donation. The mean change in blood
pressure for frequent donors was a drop of 0.82 ±1.4 mmHG (±SEM), N=11. The mean change in blood pressure
for first-time donors was a drop of 3.32±2.2 (±SEM), N=11. Mean change in systolic blood pressure was not
significantly different for frequent donors and first-time donors (p>0.05, two-tailed, unpaired t-test).
The results of the two-tailed, unpaired T-test for pre- and post-donation heart rate between frequent and first
time donors indicated that there was not a significant difference, (T-test assuming unequal variances, t=-0.41, df=40,
and p>0.05) (Figure 3).
Mean Change in Heart Rate
(BPM)
6.0
5.0
4.0
3.0
2.0
1.0
0.0
Frequent
First Time
Frequency of Donation
Figure 3. Mean change in heart rate versus frequency of donation. The mean change in heart rate for frequent
donors was an increase of 2.18±2.3 BPM (±SEM), N=11. The mean change in heart rate for first-time donors was
an increase of 3.36±1.8 BMP (±SEM), N=11. Mean change in heart rate was not significantly different for frequent
donors and first-time donors (p>0.05, two-tailed, unpaired t-test).
The results of the two-tailed, unpaired T-test for pre- and post-donation MAP between frequent and first time
donors indicated that there was not a significant difference, (T-test assuming unequal variances, t=-0.89, df=38, and
p>0.05) (Figure 4).
Mean Change in Mean Arterial
Pressure (mmHg)
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
Frequent
First Time
Frequency of Donation
Figure 4. Mean change in mean arterial pressure versus frequency of donation. The mean change in MAP for
frequent donors was a decrease of 1.18±1.2 mmHG (±SEM), N=11. The mean change in MAP for first-time donors
was a decrease of 2.97±1.6 mmHG (±SEM), N=11. Mean change in heart rate was not significantly different for
frequent donors and first-time donors (p>0.05, two-tailed, unpaired t-test).
The second set of statistical tests ran were comparing systolic and diastolic blood pressure, heart rate, and
MAP for male and females. For frequent male and female donors, there was no significant difference in the systolic
(T-test assuming unequal variances, t=0.61, df=17, and p>0.05) (Figure 5) or diastolic blood pressures (T-test
assuming unequal variances, t=-0.19, df=17, and p>0.05) (Figure 6). For first time male and female donors, there
was also no significant difference in the systolic (T-test assuming unequal variances, t=-0.16, df=20, and p>0.05)
(Figure 7) or diastolic blood pressures (T-test assuming unequal variances, t=-0.92, df=18, and p>0.05) (Figure 8).
Mean Change in Systolic Blood
Pressure (mmHg)
-2
-1
0
1
2
3
4
Male
Female
Gender
Figure 5. Mean change in systolic blood pressure versus gender for frequent donors. The mean change in systolic
blood pressure for frequent male donors was a decrease of 1.09±1.4 mmHG (±SEM), N=11. The mean change in
systolic blood pressure for frequent female donors was a decrease of 2.73±2.3 mmHG (±SEM), N=11. Mean
change in systolic blood pressure was not significantly different for frequent donors and first-time donors (p>0.05,
two-tailed, unpaired t-test).
Mean Change in Systolic Blood
Pressure (mmHg)
-2
-1
0
1
2
3
4
Female
Male
Gender
Figure 6. Mean change in systolic blood pressure versus gender for first time donors. The mean change in systolic
blood pressure for frequent male donors was a decrease of 2.55±2.5mmHG (±SEM), N=11. The mean change in
systolic blood pressure for first time female donors was a decrease of 2.00±2.4mmHG (±SEM), N=11. Mean
change in systolic blood presssure was not significantly different for frequent donors and first-time donors (p>0.05,
two-tailed, unpaired t-test).
The results of the two-tailed, unpaired T-test for pre- and post-donation diastolic blood pressure between
frequent male and female donors indicated that there was not a significant difference, (T-test assuming unequal
variances, t=-0.19, df=17, and p>0.05) (Figure 7). The results for first time male and female donors also indicated
there was not a significant difference (T-test assuming unequal variance, t=-092, df=18, and p>0.05) (Figure 8).
Mean Change in Diastolic
Blood Pressure (mmHG)
-2
-1
0
1
2
3
4
Female
Male
Gender
Figure 7. Mean change in diastolic blood pressure versus gender for frequent donors. The mean change in
diastolic blood pressure for frequent male donors was a decrease of 1.09±2.5mmHG (±SEM), N=11. The mean
change in diastolic blood pressure for frequent female donors was a decrease of 0.55±1.5mmHG (±SEM), N=11.
Mean change in systolic blood pressure was not significantly different for frequent donors and first-time donors
(p>0.05, two-tailed, unpaired t-test).
Mean Change in Diastolic Blood
Pressure (mmHG)
-3
-2
-1
0
1
2
3
4
5
Female
Male
Gender
Figure 8. Mean change in diastolic blood pressure versus gender for first time donors. The mean change in
diastolic blood pressure for frequent male donors was a decrease of 5.27±3.4mmHG (±SEM), N=11. The mean
change in diastolic blood pressure for frequent female donors was a decrease of 01.36±2.5mmHG (±SEM), N=11.
Mean change in systolic blood pressure was not significantly different for frequent donors and first-time donors
(p>0.05, two-tailed, unpaired t-test).
Heart rate also showed no significant difference between frequent male donors and frequent female donors
and between first time male donors and first time female donors. The results of the t-test for pre- and post-donation
heart rate in frequent male and female donors indicated there was no significant difference (T-test assuming unequal
variances, t=-1.31, df=15, and p>0.05) (Figure 9) nor in first time donors (T-test assuming equal variances, t=-1.07,
df=17, and p>0.05) (Figure 10).
Mean Change in Heart Rate
(BPM)
6
5
4
3
2
1
0
-1
-2
-3
-4
Female
Male
Gender
Figure 9. Mean change in heart rate versus gender for frequent donors. The mean change in heart rate for frequent
male donors was a decrease of 0.18±4.0mmHG (±SEM), N=11. The mean change in heart rate for frequent female
donors was an increase of 4.91±2.1mmHG (±SEM), N=11. Mean change in heart rate was not significantly
different for frequent male donors and frequent female donors (p>0.05, two-tailed, unpaired t-test).
Mean Change in Heart Rate
(BPM)
5
4
3
2
1
0
-1
-2
Male
Female
-3
Gender
Figure 10. Mean change in heart rate versus gender for first time donors. The mean change in heart rate for first
time male donors was an increase of 1.45±1.9mmHG (±SEM), N=11. The mean change in heart rate for first time
female donors was an increase of 5.27±3.0mmHG (±SEM), N=11. Mean change in heart rate was not significantly
different for first time male donors and first time female donors (p>0.05, two-tailed, unpaired t-test).
Mean arterial pressure also showed no significant difference between frequent male donors and frequent female
donors, nor between first time male donors and first time female donors. The results of the t-test for pre- and postdonation MAP in frequent male and female donors indicated there was no significant difference (T-test assuming
unequal variances, t=0.09, df=18, and p>0.05) (Figure 11). In first time donors, the t-test indicated there was no
significant difference (T-test assuming unequal variances, t=-0.83, df=18, and p>0.05) (Figure 12).
Mean Change in MAP (mmHG)
-3.50
-3.00
-2.50
-2.00
-1.50
-1.00
-0.50
0.00
0.50
1.00
Female
Male
1.50
Gender
Figure 11. Mean change in MAP versus gender for frequent donors. The mean change in MAP for frequent male
donors was a decrease of 1.06±1.9mmHG (±SEM), N=11. The mean change in heart rate for frequent female
donors was a decrease of 1.28±2.7mmHG (±SEM), N=11. Mean change in heart rate was not significantly different
for frequent male donors and frequent female donors (p>0.05, two-tailed, unpaired t-test).
Mean Change in MAP (mmHG)
-8.00
-7.00
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
Male
Female
Gender
Figure 12. Mean change in MAP versus gender for first time donors. The mean change in MAP for first time male
donors was a decrease of 4.35±2.7mmHG (±SEM), N=11. The mean change in heart rate for first time female
donors was a decrease of 1.58±1.9mmHG (±SEM), N=11. Mean change in MAP was not significantly different for
frequent male donors and frequent female donors (p>0.05, two-tailed, unpaired t-test).
Discussion
Our results indicate that there is not a significant difference between the pre- and post-donation systolic and
diastolic blood pressures, heart rate, or MAP for frequent donors and first-time donors. Additionally, there is not a
significant difference between pre- and post-donation systolic and diastolic blood pressures, heart rate, or MAP for
males and females. These findings indicates that no matter how often a person experiences blood loss and the
despite different genders, the body does not physiologically adapt to respond to the effects of blood loss faster.
Based on this result, the hypothesis and prediction of this study are not supported.
As previously discussed, the loss of blood during donation is enough to cause physiologic responses in a body.
One such response is a lower blood pressure (McGuill, 1989). Another physiological response is the activation of
the baroreceptor response to changes in blood pressure. With a decrease in blood pressure, the baroreceptors would
send a signal to cause the heart to beat faster (Parati, 218). If adaptation were occurring as a result of frequent blood
loss, then the baroreceptors would reset to compensate for the changes in blood pressure. With the frequent
lowering of blood pressure, the baroreceptors would reset the response threshold to the lower blood pressure.
However, a previous study found that baroreceptor reflex sensitivity does not change as blood pressure values
change (Parati, 219). In fact, baroreceptor mechanisms may only account up to 25% of the overall changes in blood
pressure (Mancia, 152). Therefore, blood pressure changes are much more susceptible to physical activity and
emotions.
As previously discussed, heart rate increases due to the baroreceptor response. Our results indicate that there
was no significant difference for frequent donors and first time donors. If adaptation occurred, then the heart rate for
frequent donors would be lower than the heart rate for first time donors since it would take first time donors a longer
time to recuperate.
Mean arterial pressure (MAP) which is calculated from systolic pressure and diastolic pressure showed no
significant difference between frequent donors and first time donors. MAP is the mean blood pressure over one
heartbeat (This description of MAP is left out of the intro, maybe you should add it). Since there was no significant
difference between systolic and diastolic pressures pre and post donation for frequent and first time donors it follows
that there would be no significant difference in the blood pressure of one heat beat. The physiological responses in
first time donors and frequent donors are not significantly different.
If the body were adapting to a reduced blood volume, the physiological response would have been a smaller
change in systolic and diastolic blood pressure in the subjects who donated more frequently. However, this finding
was not the result of the present study. Therefore, this study is suggestive that people do not adapt physiologically
to blood loss regardless of frequency of occurrence.
Another form of adaptation is evolutionary adaptation. Evolutionary adaptation (i.e., natural selection) is the
genetic success of traits that allows a species to be better adapted to the environment. Blood donation is a voluntary
activity and therefore, is not an environmental stress to which a species must adapt in order to survive. Since natural
selection is the mechanism of adaptation for a species and blood donation is not an environmental stress, it follows
that humans are not inclined to adapt to blood loss.
The findings of this study also indicate that both frequent and first-time donors should be monitored after
donating blood. The loss of blood can cause a donor to feel light headed or to have a syncopal episode. Since both
frequent and first-time donors sustain changes in blood pressure, both types of donors should be kept and monitored
for a period of time after donation, to ensure there will not be an adverse reaction.
Further investigation should be conducted to verify these results. Additional studies should consist of a larger
sample size. Alternative studies could include a comparison of the blood pressure recovery times to pre-donation
levels for frequent versus first-time donors. Although the instantaneous change in blood pressure is larger for
frequent donors, a difference in the time for post donation blood pressure of frequent and first-time donors to return
to the pre-donation blood pressure could be an indicator of adaptation. Additionally, as mentioned in the
introduction, several physiological effects result from blood loss. This study determined that there is not a
significant difference in pre- and post-donation blood pressures for frequent and first-time donors. However, further
investigation is required to determine if adaptation is occurring with regard to the other blood loss compensatory
responses, such as heart rate, arteriolar constriction, and vasoconstriction.
Acknowledgements
The authors wish to thank Kimberly Bursk, R.N. and the staff at the American Red Cross donor centers. Ms.
Bursk was instrumental in assisting with the collection of data and the completion of this study.
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Review Form
Department of Biological Sciences
Saddleback College, Mission Viejo, CA 92692
Author (s): Stephanie Melton and Jessica Ochoa
Title: The effect of blood donation frequency and gender on physiological response to blood loss
Summary
Summarize the paper succinctly and dispassionately. Do not criticize here, just show that you understood the paper.
This paper was comparing first time donors and frequent donors with several different
hypotheses. The first hypothesis tested was comparing the change in systolic blood pressure (bp) in
frequent and first time donors. The second hypothesis tested was change in diastolic bp in frequent and
first time donors. The third hypothesis tested was change in heart rate (hr) when compared to frequent
and first time donors. The fourth hypothesis tested was the change in mean arterial pressure (MAP). The
fifth hypothesis being tested was change in systolic bp compared genders of frequent donors. The sixth
hypothesis tested was the change in systolic bp compared genders of first time donors. The seventh
hypothesis tested was the change in diastolic bp compared genders of frequent donors. The eighth
hypothesis tested was the change in diastolic bp compared genders of first time donors. The ninth
hypothesis tested was the change in hr comparing genders of frequent donors. The tenth hypothesis
tested was the change in hr comparing genders of first time donors. The eleventh hypothesis being
tested was the change in MAP comparing the genders of frequent donors. The twelfth hypothesis was
comparing the change in MAP comparing the genders of first time donors. In all the hypothesizes tested
there was no difference.
General Comments
Generally explain the paper’s strengths and weaknesses and whether they are serious, or important to our current
state of knowledge.
- Is MAP for all subjects or just an individual? I saw in the methods and materials that you had 30 first-time
donors and 30 frequent donors. In your stats your sample size was N=11. Were you not able to use all 30?
Why?
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This paper was written very well. Great sources and for the most part had good info about everything. I
think though that this paper was a little longer than it needed to be. There we a lot of tests done just to
show there were no differences.
Technical Criticism
Review technical issues, organization and clarity. Provide a table of typographical errors, grammatical errors, and
minor textual problems. It's not the reviewer's job to copy Edit the paper, mark the manuscript.
X This paper was a final version
This paper was a rough draft