Gender differences in perception of effectiveness of using statistical software in learning statistics.
Freeman, Gordon ; Wyatt, Jacqueline ; Adams, C. Nathan 等
INTRODUCTION
In 1973, Lucy W. Sells identified mathematics as the "critical
filter" that prohibits many women from entering the ranks of higher
paying, prestigious occupations, and since the publication of that
seminal work there has been a great emphasis upon gender differences in
mathematical performance.
Studies of gender differences in mathematics performance indicate
that females "showed a slight superiority in computation in
elementary school and middle school. There were no gender differences in
problem solving in elementary or middle school; differences favoring men
emerge in high school and college" (Hyde, Fennama & Lamon,
1990). Leo (1999) states that females lag behind males in math and
science test scores. Enzensberger (1999) goes so far as to state
"...[mathematical ability] is established genetically in the human
brain." These conflicting data are rather typical of the
disagreement in literature regarding the evidence for a male advantage
in math performance (Casey, Nuttall & Pezaris, 1997). They do state
that there is a gender difference favoring males among high-ability
students at measured by the Mathematics Scholastic Aptitude Test (SAT-M), and this has major implications for women's entrance into
math-science fields.
There have been fewer studies concerning gender difference in the
use and acceptance of computers. Dambrot, et al (1985) states that
"there is every reason to believe that people in general and women
in particular who have had problems with mathematics will find working
with computers even more difficult and threatening". A study by
Igbaria and Parasuraman (1989) indicates that there is a moderate
connection between math anxiety and computer anxiety with managers
OVERVIEW OF CURRICULUM CONSIDERATIONS
Virtually all universities and colleges require students to take
one or more statistics courses in many different majors, e.g.,
education, psychology, business, etc., for the non-specialist, and most
Schools of Business require one or more courses in computer literacy.
This paper focuses on whether there are gender differences in the
perception of how helpful a statistical software package (MINITAB) is in
learning statistical procedures for those non-specialists who are
majoring in a field within business. The traditional method currently
used in teaching statistics is widely viewed as being ineffective (Cobb,
1993; Mosteller, 1988).
The recommendations of the American Statistical Association and the
Mathematical Association of America (ASA/MAA, 1996) Committee on
Undergraduate Statistics should be integrated into the methodology
utilized for teaching statistical courses. These recommendations are to
teach statistical thinking; to emphasize more data and concepts, less
theory and fewer recipes; and, to foster active learning. There are
several approaches for teaching statistics to the non-specialists: (1)
the use of manual calculations by using a hand-held calculator, (2) the
use of a computer software package, and (3) a combination using both the
manual and computer software package. A computer software package, such
as MINITAB, could be selected which would enhance the student's
ability to visualize and explore basic statistical concepts. MINITAB
provides the means to generate the output and then allows the student to
become statistical thinkers.
Many students who enroll in the statistics courses do so without
sufficient computer literacy skills, and, therefore, spend their time
attempting to master those requisite computer skills, ultimately
neglecting the in-dept understanding of the statistics which was the
objective of the course. Students appear to be more interested in
acquiring computer skills than mathematical skills, probably because it
is much more fashionable to discuss computers than statistics, and, very
importantly, students are aware that computer literacy skills are
advertised as a prerequisite for most jobs whereas they seldom find
mathematical competencies advertised as a prerequisite for jobs.
A study of undergraduates by Dambrot, et al (1985) indicates that
computer aptitude was strongly related to mathematics ability and
experience. The results show that females held more negative attitudes
toward computers, scored lower in computer aptitude, and had less
prerequisite mathematics ability and course work.
OVERVIEW OF PRESENT STUDY
Middle Tennessee State University (MTSU) students must take
advanced business statistics (Statistical Methods II) which covers
topics in hypothesis testing and regression analysis after taking the
introductory statistics course. While each faculty member teaching these
courses must cover specific core topics, the method of presentation is
an individual decision. Teaching techniques range from those faculty
members who make minimal use of a statistical software package (MINITAB)
to those who make minimal use of manual calculations (hand-held
calculators).
The MTSU statistics faculty have had considerable discussions on
teaching methodologies and outcomes, particularly with regard to the
emphasis placed upon statistical software in teaching statistical
procedures. In an attempt to satisfy faculty at both ends of the
continuum, many statistics faculty members introduce new topics to
students with manual methods (hand-held calculators) then reinforce the
topic with the use of a computer statistical package (MINITAB).
The College of Business at MTSU is AACSB accredited and has a
state-of-the-art new building with computer labs and networked
telecommunication facilities. Each classroom has multimedia, a
projector, and is networked so that computer software is immediately
available to the instructor and students alike. MINITAB for Windows is
used in the classrooms and in the computer laboratory, making MINITAB
available both in class and for out-of class assignments. In addition to
the computer lab, there is a separate business statistics lab in the
same locale as the offices of the faculty members who teach the
statistical courses. The business statistics lab is staffed by graduate
assistants whose job it is to assist students who require additional
information, as well as help them utilize computer statistical packages.
RESEARCH METHODOLOGY
A questionnaire was created and administered to seven sections of
the advanced statistics course (Statistical Methods II) during the last
scheduled class day in the fall semester of 1998, and another seven
sections during the last class day in the spring semester of 1999. The
students were asked to relate their views on the effectiveness of the
dual method of presentation, i.e., utilizing both the manual (hand-held
calculators) and a computer software package, as well as their
evaluation of the effectiveness of more or less presentation with either
of the methods. Various demographic data were also collected, including
gender (See Appendix for Questionnaire). A Likert-type scale from 1
(strongly disagree) to 7 (strongly agree) was utilized in an effort to
determine the student's perceptions of the benefits of one teaching
methodology over the others, and whether these results would differ by
gender.
DATA ANALYSIS
All statements in which the male and female responses differed
significantly were identified ([alpha] = 0.05). The responses of both
genders to each of the twenty-six statements were tested using an
Anderson-Darling test for normality, and all twenty-six statements were
found to have responses that were not normally distributed at the 0.000
level of significance. Even the robustness of the normality assumption
in ANOVA tests was not expected to compensate for that lack of
normality, so the Mann-Whitney-Wilcoxon test was used to check for
gender differences. The results for the nine statements showing
significant ([alpha] = 0.05) gender differences are presented in Table
1.
To rank these nine statements by the degree of gender difference
(with 1 being the rank of the statement having the largest degree of
gender difference) Z-values for the normal approximation to the
Mann-Whitney-Wilcoxon test were calculated. For the
Mann-Whitney-Wilcoxon test, the normal approximation formula used was:
Z = [M--([n.sub.1])([n.sub.T] +
1)/2]/sqrt[([n.sub.1])([n.sub.2])([n.sub.T] + 1)/12],
where M was the computed value of the Mann-Whitney-Wilcoxon test;
[n.sub.1] was the number of female responses;
[n.sub.2] was the number of male responses; and
[n.sub.T] was the sum of [n.sub.1] and [n.sub.2].
These Z-values and their ranks are shown in Table 1. Note that all
the Z-values are negative. A negative Z-value indicates that the typical
female response to each of these nine statements was lower than the
typical male response.
Of the nine statements in Table 1, eight (18--25) dealt with the
helpfulness of MINITAB with respect to a particular subset of
statistical procedures. The other statement, (17), " It is easier
to learn how to use MINITAB to perform a hypothesis test than it is to
learn how to perform the hypothesis test manually" while more
general, showed the least amount of gender difference in the group.
With regard to statements 18--25, two observations deserve special
mention. The two statements that show the highest degree of gender
difference are {23 and 22}. These two state that MINITAB was
particularly helpful in understanding multiple-sample parametric and
multiple-sample non-parametric tests. The four statements showing the
highest degree of gender difference are {23, 22, 19 and 21}. This set of
four statements includes all the types of non-parametric tests covered
in the QM 362 course.
The results shown in Table 1 illustrate which statements in the
survey have the largest amount of gender difference, but does not
illustrate the type of gender difference. The negative Z-values show
that the typical female response to a statement is significantly less
than the typical male response for each of the nine statements in Table
1. However, it cannot be determined if both genders agreed, both genders
disagreed, or the males agreed and the females disagreed. Quantification requires the use of additional hypothesis tests. The information
provided by these tests allows the determination of the types of the
nine gender differences shown in the responses to the statements in
Table 1.
The Likert-type scale used to measure the degree of agreement
(disagreement) had a midpoint of 4, so a null hypothesis that the
midpoint of responses = 4 for the female responses and the male
responses was tested for each of these nine statements. What test
statistic should be used for these tests?
Since the Anderson-Darling tests indicated that the statement
responses for each gender were not normally distributed, a t-test was
not appropriate. The nagging question that remained was whether the
responses constituted at least an interval level of measurement and
justified the use of the Wilcoxon Signed-Rank test. The use of the Sign
test for such responses is clearly justified, but is it the best test?
It was decided to perform both the Wilcoxon Signed-Rank test and the
Sign test on the female and male responses to each of these nine
statements and be conservative in the interpretation of the results.
Both tests had to show a significant effect or it would not be reported
as significant. See Table 2.
Since two-tailed hypothesis tests were being used, the p-values of
the tests show evidence of significant agreement or disagreement, but
the p-value by itself does not indicate which one. It could mean
significant agreement in one case and significant disagreement in
another case. Again we used the Z approximations to the two test
statistics to tell if there was agreement (positive Z-value) or
disagreement (negative Z-value) and to make it easy to rank the degree
of the agreement or the degree of disagreement.
For the Wilcoxon Signed-Rank test, the normal approximation formula
is:
Z = [W--(n')(n' + 1)/4]/sqrt[(n')(n' +
1)(2n' + 1)/24], where n' is the number of responses that
differ from the hypothesized median. These Z-values and their ranks and
are shown in Table 3.
For the Sign test, the normal approximation formula is:
Z = [Above--(n')/2]/sqrt[(n')/4], where n' is the
number of responses that differ from the hypothesized median. These
Z-values and their ranks and are shown in Table 3.
The ranks in Table 3 represent the level of disagreement with the
corresponding statement. The statement disagreed with at the highest
level (most negative Z-value) received a rank of 1 and so on. Positive
Z-values indicated agreement. Using the p-values in Table 2 and the sign
of the Zvalues in Table 3, Table 4 was constructed. It shows the types
of the gender differences for the nine statements that showed a
significant gender difference.
In seven out of the nine statements showing significant gender
differences (17--23), both genders disagreed with the statements with
the females disagreeing more strongly. In statement 24, the females
significantly disagreed, while the males insignificantly agreed. In
statement 25 the females insignificantly disagreed, while the males
insignificantly agreed. In all nine statements showing significant
gender differences, the female responses showed more disagreement that
the male responses did.
Eight of the nine statements showing significant gender differences
(18--25) dealt with the helpfulness of MINITAB with respect to a
particular subset of statistical procedures. The statistical procedures
mentioned in these eight statements were broken down into two groups:
the parametric statistical procedures {18, 20, 22, 24 and 25} and the
non-parametric statistical procedures {19, 21 and 23}. The list {18, 20,
22, 24 and 25} orders the parametric statistical procedures by
increasing complexity. Likewise, the list {19, 21 and 23} orders the
non-parametric statistical procedures by increasing complexity. Table 5
was created to show each of the two groups of statistical procedures
with the corresponding survey statements ordered by increasing
complexity of the tests. The level-of disagreement ranks from Table 3
were inserted in the same row with the corresponding statement. The
purpose was to see how the level of difficulty of the test correlated with the level of disagreement with the statement shown by each gender.
Regardless of the test used to obtain the level-of-disagreement ranks or
the gender, the ranks were perfectly correlated with the level of
difficulty in the parametric statistical procedures. As the level of
difficulty of the parametric statistical procedure increased, the level
of disagreement with the associated survey statement decreased.
Regardless of the test used to obtain the level-of-disagreement ranks
for the female responses, the ranks were perfectly correlated with the
level of difficulty in the non-parametric statistical procedures. Using
the Wilcoxon Signed-Rank test to obtain the level-of-disagreement ranks
for the male responses, the ranks were perfectly correlated with the
level of difficulty in the non-parametric statistical procedures. The
only case where the correlation was not perfect (R = 0.5 if least
complex gets a rank of 1) was when the Sign Test was used to obtain the
level-of-disagreement ranks for the male responses.
DISCUSSION OF RESULTS
Only nine statements showed a significant difference at the .05
level of significance. In all statements where there was a clear gender
difference in the responses, the females had a higher level of
disagreement with the statement than the males. If these nine statements
are ordered by the degree of significance with the statements having the
most significant gender differences being listed first, the order of the
statements is: {23, 22, 19, 21, 20, 24, 25, 18 and 17}. In statements 23
and 22 both genders tended to disagree with these two statements, but
the level of the female disagreement was significant ([alpha] = 0.05).
This result suggests the conclusion that females find MINITAB to be of
less help than males in understanding multiple-sample statistical tests.
All three of the survey statements that mention non-parametric
tests {19, 21 and 23} are in the "top four" of the nine
statements with significant gender differences. Both genders tended to
disagree with these three statements, but the level of the female
disagreement was significantly more than that of the males. This result
suggests the conclusion that females find MINITAB to be of less help
than males in understanding non-parametric statistical tests.
In seven out of the nine statements showing significant gender
differences (17--23), both genders were disagreeing with the statements
with the females disagreeing more strongly. Of these seven statements,
19, 21, and 23 were addressed as a group above. A similar group is the
group of the only three survey statements that specifically refer to
parametric tests. Both genders tended to disagree with these three
statements, but the level of the female disagreement was significantly
more than that of the males. This result suggests the conclusion that
females find MINITAB to be of less help than males in understanding
one-sample, two-sample and multiple-sample parametric tests.
The other two statements dealt with regression. In statement 24,
the females significantly disagreed, while the males insignificantly
agreed. This result suggests the conclusion that males see some benefit
in using MINITAB to help them understand simple linear correlation and
regression, but the females do not. In statement 25 the females
insignificantly disagreed, while the males insignificantly agreed. This
result suggests the conclusion that the females do not see as much
benefit in using MINITAB to help them understand multiple regression
analysis as the males do.
In both parametric tests and non-parametric tests, the females tend
to see MINITAB of being less helpful in their understanding of those
statistical procedures than the males do. However, as the tests get more
complex, both genders tend to disagree less with the statement that
MINITAB aids understanding.
The females continue to disagree that MINITAB aids their
understanding even up to the complexity of regression analysis, while
the males start to agree that MINITAB is helpful when the complexity of
regression analysis is reached.
SUMMARY AND CONCLUSIONS
A questionnaire was administered to students at MTSU who were
enrolled in advanced statistics in the fall of 1998 and the spring of
1999 in an effort to investigate if there were gender differences in the
perception of effectiveness of various methodologies of teaching
advanced business statistics. Statistical analysis of the results
indicates that there are differences in gender acceptance and opinion
regarding the understanding of statistics when using statistical
software (MINITAB).
In both parametric tests and non-parametric tests, the females tend
to see MINITAB as being less helpful in their understanding of those
statistical procedures than do the males. However, as the tests get more
complex, both genders tend to disagree less with the statement that
MINITAB aids understanding. The females continue to disagree that
MINITAB aids their understanding even up to the complexity of regression
analysis, while the males start to agree that MINITAB is helpful when
the complexity of regression analysis is reached.
Further research is suggested to investigate the relationship
between student's perception and actual performance using different
teaching methodologies. Outcome assessment studies could be undertaken
in order to analyze this relationship.
REFERENCES
American Statistical Association and the Mathematical Association
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departments in undergraduate mathematical sciences ASA/MAA joint
committee on undergraduate statistics.
[Online],(http://www.maa.org/data/guidelines/asa%5Fresponse.html).
Casey, M. B., Nuttal, R. L. & Pezaris, E. (1997). Mediators of
gender differences in mathematics college entrance test Scores: A
Comparison of spatial skills with internalized beliefs and anxieties.
Developmental Psychology, 33(4), 669-680.
Cobb, G. W. (1993). Teaching Statistics. In Heeding the Call for
Change, ed. Lynn Steen, (MAA Notes No. 22). Washington: Mathematical
Association of America, 3-23.
Dambrot, F. H., Watkins-Malek, M. A., Silling, S. M., Marshall, R.
S. & Enzensberger, H. M.. (1999). Why no one knows we're living
in a golden age of mathematics. Chronicle of Higher Education, XLV(34),
B9.
Hyde, J. S., Fennema, E. & Lamon, S. J. (1990). Gender
differences in mathematics performance: A meta-analysis. Psychological
Bulletin, 107(2), 139-155.
Iggbaria, M. & Parasuraman, S. (1989). A path analytic study of
individual characteristics, computer anxiety and attitudes toward
microcomputers. Journal of Management, 15(3), 373-388.
Leo, J. (1999). Gender wars redux. U.S. News & World Report,
126(7), 24.
Mosteller, F. (1988). Broadening the scope of statistics and
statistical education. The American Statistician, 42, 93-99.
Sells, L. W. (1973). High school mathematics as the critical filter
in the job market. In R. T. Thomas (Ed.), Developing opportunities for
minorities in graduate education (pp. 37-39). Berkeley: University of
California Press.
Gordon Freeman, Middle Tennessee State University
Jacqueline Wyatt, Middle Tennessee State University
C. Nathan Adams, Middle Tennessee State University
Wayne Gober, Middle Tennessee State University
APPENDIX
Q.M. 362 CLASSES
Student Perception of Learning: Comparing Manual Procedures withMINITAB
In many Q.M. 362 classes a statistical topic is
introduced using manual techniques with hand-held calculators. Once the
basic principles and
procedures of the technique are presented MINITAB is then used to work
the same or similar problems. In an effort to ascertain the benefits
students obtain from the two approaches the following questionnaire
has been devised.
Please circle your response to each of the following questions on a
scale from 1 (strongly disagree) to 7 (strongly agree)
Strongly Disagree Strongly Agree
1. I learn more from manual calculations than 1 2 3 4 5 6 7
from problems solved with MINITAB
2. I retain more knowledge of statistical 1 2 3 4 5 6 7
techniques from problems worked with
MINITAB than problems worked manually
3. Introduction of statistical topics using 1 2 3 4 5 6 7
manual procedures provide a good
understanding of the rationale and
techniques of the topics
4. Reinforcement of statistical topics using 1 2 3 4 5 6 7
MINITAB after manual techniques have been
covered strengthens and enhances my
understanding of the topics
5. Manual exercises increased my knowledge of 1 2 3 4 5 6 7
each statistical procedure
6. MINITAB exercises increased my knowledge 1 2 3 4 5 6 7
of each statistical procedure
7. Manual computations distracted me in 1 2 3 4 5 6 7
understanding and mastering concepts of
statistical methodology
8. MINITAB procedures distracted me in 1 2 3 4 5 6 7
understanding and mastering concepts of
statistical methodology
9. I would prefer greater emphasis on manual 1 2 3 4 5 6 7
calculations in the course
10. MINITAB procedures were clear and 1 2 3 4 5 6 7
understandable
11. Manual procedures were clear and 1 2 3 4 5 6 7
understandable
12. MINITAB procedures challenge and 1 2 3 4 5 6 7
encourage independent thought
13. In the classroom MINITAB allows for 1 2 3 4 5 6 7
better structure of content
14. In the classroom MINITAB allows for 1 2 3 4 5 6 7
standardized delivery of content
15. In the classroom MINITAB allows for more 1 2 3 4 5 6 7
interesting instruction
16. In the classroom MINITAB allows for 1 2 3 4 5 6 7
longer retention of course material
17. It is easier to learn how to use MINITAB 1 2 3 4 5 6 7
to perform a hypothesis than it is to learn
how to perform the hypothesis test manually
18. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding one-sample parametric tests
19. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding one-sample non-parametric
tests such as the Wilcoxon Signed Ranks
test
20. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding two-sample parametric tests
such as two-sample t test with pooled
variance
21. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding two-sample non-parametric
tests such as the Mann-Whitney test
22. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding multiple-sample parametric
tests such as ANOVA
23. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding multiple-sample non-
parametric tests such as the Kruskal-Wallis
test
24. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding simple linear correlation and
regression
25. MINITAB was particularly helpful in 1 2 3 4 5 6 7
understanding multiple regression analysis
26. At the beginning of this course I was 1 2 3 4 5 6 7
already familiar with some computer
software
TABLE 1
Mann-Whitney-Wilcoxon Test
Test of median of females = median of males versus median of females
not = median of males
Mann-
N N Whitney-
N for for Wilcoxon
Statement Missing Females Males Statistic
C17 1 130 105 14274.5
C18 0 130 106 14331.0
C19 0 130 106 13859.0
C20 0 130 106 13929.0
C21 0 130 106 13900.5
C22 1 130 105 13767.5
C23 0 130 106 13794.0
C24 0 130 106 14002.5
C25 0 130 106 14183.0
Z for
Mann-
Female Male Whitney- Z
Statement P Median Median Wilcoxon Ranks
C17 0.0398 3.000 4.000 2.05647 9
C18 0.0396 3.000 3.500 2.05871 8
C19 0.0031 3.000 4.000 2.96348 3
C20 0.0047 3.000 4.000 2.82929 5
C21 0.0039 3.000 4.000 2.88393 4
C22 0.0024 3.000 4.000 3.03500 2
C23 0.0020 3.000 4.000 3.08807 1
C24 0.0072 4.000 4.000 2.68841 6
C25 0.0192 4.000 5.000 2.34241 7
TABLE 2
Nine Statements With The Most Significant Gender Differences
Females
Wilcoxon
Signed-
N for Rank
Statement Test Statistic P Above P
C23 92 490.5 0.000 18 0.0000
C22 97 950.5 0.000 25 0.0000
C19 91 350.0 0.000 11 0.0000
C21 93 394.0 0.000 15 0.0000
C20 93 372.0 0.000 15 0.0000
C24 99 1412.0 0.000 39 0.0444
C25 104 2215.5 0.096 52 1.0000
C18 95 399.0 0.000 14 0.0000
C17 107 1721.5 0.000 37 0.0020
Males
Wilcoxon
Signed-
N for Rank
Statement Test Statistic P Above P
C23 68 814.0 0.028 29 0.2751
C22 73 1259.5 0.619 35 0.8149
C19 77 904.5 0.002 30 0.0682
C21 70 758.5 0.005 25 0.0232
C20 75 851.0 0.002 29 0.0647
C24 85 1871.5 0.849 49 0.1931
C25 84 2069.5 0.205 54 0.0121
C18 74 670.5 0.000 21 0.0003
C17 89 1848.0 0.529 44 1.0000
TABLE 3
Nine Statements with the Most Significant Gender Differences
Females
Z
N for Z for
Statement for Females W Rank Above Rank
C23 92 -6.41909 5 -5.83840 5
C22 97 -5.13108 6 -4.77213 6
C19 91 -6.89863 3 -7.23317 1
C21 93 -6.86430 4 -6.53280 3.5
C20 93 -6.94859 2 -6.53280 3.5
C24 99 -3.71018 7 -2.11058 8
C25 104 -1.66842 9 0.00000 9
C18 95 -6.98201 1 -6.87405 2
C17 107 -3.62860 8 -3.19023 7
Males
N Z Z
for for for
Statement Males W Rank Above Rank
C23 68 -2.19362 5 -1.21268 5
C22 73 -0.50028 7 -0.35112 6
C19 77 -3.03125 2 -1.93733 4
C21 70 -2.83246 4 -2.39046 2
C20 75 -3.03104 3 -1.96299 3
C24 85 0.19280 8 1.41005 8
C25 84 1.26881 9 2.61861 9
C18 74 -3.86265 1 -3.71992 1
C17 89 -0.63211 6 -0.10600 7
TABLE 4
Nine Statements with the Most Significant Gender Differences
Females
[alpha] = 0.05
A = Agree S = significant
Statement D = Disagree I = insignificant
C23 D S
C22 D S
C19 D S
C21 D S
C20 D S
C24 D S
C25 D I
C18 D S
C17 D S
Males
[alpha] = 0.05
A = Agree S = significant
Statement D = Disagree I = insignificant
C23 D I
C22 D I
C19 D I
C21 D S
C20 D I
C24 A I
C25 A I
C18 D S
C17 D I
TABLE 5
Level-of-disagreement Ranks Catagorized
Parametric Statistical Procedures
Females Males
Statement Wilcoxon Sign Wilcoxon Sign
Ranks Ranks Ranks Ranks
C18 1 2 1 1
C20 2 3.5 3 3
C22 6 6 7 6
C24 7 8 8 8
C25 9 9 9 9
Non-Parametric Statistical Procedures
Females Males
Statement Wilcoxon Sign Wilcoxon Sign
Ranks Ranks Ranks Ranks
C19 3 1 2 4
C21 4 3.5 4 2
C23 5 5 5 5