CRJ_575_Mod_6_DiscussionFinalToPost
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Colorado State University, Global Campus *
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575
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Statistics
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Jan 9, 2024
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Hypothesis and null hypothesis:
Hypothesis:
There is a significant difference in the mean GPA scores among the different racial
groups. In statistical terms, the research hypothesis can be viewed as follows: If 1
μ
1, 2
μ
2, and
3
μ
3 represent the average GPAs of Black, White, and Hispanic students respectively, the research
hypothesis can be stated as at least one of the population means (1
μ
1, 2
μ
2, or 3
μ
3) is different
from the others (Haans, 2019) suggesting that at least one of these racial groups have a different
average GPA compared to the others.
Null Hypothesis (HO
): There are no significant differences in mean GPA scores among the
different racial groups. The null hypothesis
μ
1=
μ
2=
μ
3 represents the average GPAs for Black,
White, and Hispanic students. Both hypotheses and analysis performed are based on data
acquired from the data file mtf11sdss.sav (Colorado State University Global, n.d.)
Summary of ANOVA results:
Between groups: SS = 6.0001, df = 2, MS = 3.001, F = 7.318, p > .001
Within groups: SS = 451.018, df = 1100, MS = .410
Total: SS = 457.020, df = 1102
Interpretation:
The one-way ANOVA tests whether there are any statistically significant
differences between the means of the GPA scores across the three racial groups (Chen et al.,
2018). The F-statistic is 7.318 with 2 and 1100 degrees of freedom between and within groups.
The p-value (<.001) is less than the chosen significance level of 0.05, indicating that there is a
statistically significant difference in mean GPA scores among different racial groups.
Effect sizes
: Eta-squared
(η²) = 0.013 represents the proportion of the total variance in GPA
scores that is associated with the variance between the racial groups (Abebe, 2019). Roughly
speaking, 1.3% of the variance in GPA scores can be attributed to the differences between racial
groups.
Omega-squared (ω²) = 0.011 (Fixed-effect model)
, which is similar to Eta-squared, represents
the proportion of the total variance in GPA scores accounted for by the variance between racial
groups.
As a result of the ANOVA, there is a statistically significant difference in mean GPA scores
among racial groups.
Descriptive Statistics:
Black (1): Mean GPA = 3.0572, SD = 0.63440
White (2): Mean GPA = 3.2323, SD = 0.63649
Hispanic (3): Mean GPA = 3.0905, SD = 0.66169
These are values that show the means and standard deviations of GPA scores for each racial
group.
Post Hoc Tests (Tukey’s HSD):
Significant mean differences were found between Black and
White (p =.0004) and between White and Hispanic (p = .021) groups.
There is no significant difference between Black and Hispanic groups (p = .880). Tukey’s HSD
test helped to identify which specific groups are different from each other regarding GPA scores.
Homogenous Subsets:
There are three subsets based on Tukey’s HSD with indicate groups with
similar mean GPA scores: Subset 1 (Black (3.0572) and Hispanic (3.0905) and Subset 2: White
(3.2323)
Both the ANOVA and Tukey’s HSD test
revealed that there are significant differences in mean
GPA scores between Black and White students, as well as between White and Hispanic students.
There did not show significant difference in mean GPA scores between Black and Hispanic
students. The homogenous subsets further support the findings by grouping students with similar
GPA scores together.
Overall summary:
The analysis of high school GPA scores across racial groups (Black, White,
and Hispanic) yielded a statistically significant overall difference which was determined by the
one-way ANOVA (F(2,100) = 7.318, p<.001). Using Tukey’s Honestly Significant Difference
(HSD) post hoc test revealed significant mean differences between Black and White groups (p
= .004) and between White and Hispanic groups (p = .021). There was no significant difference
in mean GPA scores between Black and Hispanic groups (p = .880).
Conclusion
: Based on the results generated during my analysis and taking into account the
hypotheses, one could conclude that there is enough evidence to reject the null hypothesis as
there is a statistically significant difference in mean high school GPA scores among racial
groups.
However, if the p-value was greater than the chosen significance level (usually 0.05), there
would not be enough evidence to reject the null hypothesis as there would be no significant
difference in mean high school GPA among racial groups. My analysis shows a p-value less than
0.001 allowing me to reject the null hypothesis.
Table 1
ANOVA One-way with effect sizes and descriptives
Oneway
ANOVA
High School GPA (recoded from "grade")
Sum of
Squares
df
Mean
Square
F
Sig.
Between
6.001
2
3.001
7.318
<.001
Groups
Within Groups
451.018
1100
.410
Total
457.020
1102
ANOVA Effect Sizes
a
Point
Estimate
95% Confidence
Interval
Lower
Upper
High School GPA
(recoded from "grade")
Eta-squared
.013
.002
.028
Epsilon-squared
.011
.001
.027
Omega-squared Fixed-
effect
.011
.001
.027
Omega-squared
Random-effect
.006
.000
.014
a. Eta-squared and Epsilon-squared are estimated based on the fixed-effect model.
Oneway
Descriptives
High School GPA (recoded from "grade")
N
Mean
Std.
Deviation
Std. Error
95% Confidence Interval for
Mean
Lower Bound
Upper Bound
BLACK:(1)
166
3.0572
.63440
.04924
2.9600
3.1544
WHITE:(2)
758
3.2323
.63649
.02312
3.1869
3.2777
HISPANIC:
(3)
179
3.0905
.66169
.04946
2.9929
3.1881
Total
1103
3.1830
.64399
.01939
3.1449
3.2210
Descriptives
High School GPA (recoded from
"grade")
Minimum Maximum
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BLACK:(1)
1.00
4.00
WHITE:(2)
1.00
4.00
HISPANIC:
(3)
1.00
4.00
Total
1.00
4.00
ANOVA
High School GPA (recoded from "grade")
Sum of
Squares
df
Mean
Square
F
Sig.
Between
Groups
6.001
2
3.001
7.318
<.001
Within Groups
451.018
1100
.410
Total
457.020
1102
ANOVA Effect Sizes
a
Point
Estimate
95% Confidence
Interval
Lower
Upper
High School GPA
(recoded from "grade")
Eta-squared
.013
.002
.028
Epsilon-squared
.011
.001
.027
Omega-squared Fixed-
effect
.011
.001
.027
Omega-squared
Random-effect
.006
.000
.014
a.
Eta-squared and Epsilon-squared are estimated based on the fixed-effect model.
Note
. Adapted from
Adapted from
Data Sets and Codebooks
, by Colorado State University
Global, n.d., Canvas (
https://csuglobal.instructure.com/courses/81945/modules
) and
[DataSet1]
C:\Users\SnS_M\OneDrive\Desktop\CRJ_575_Analytical Methods\Datasets
Codebooks\mtf11sdss.sav. Data analytics were performed using IBM SPSS statistics for Windows
(Version 28.0) [Computer Software] by IBM (https://www.ibm.com/products/spss-statistics).
Table 2
Post Hoc Tests
Post Hoc Tests
Multiple Comparisons
Dependent Variable: High School GPA (recoded from "grade")
Tukey HSD
(I) Respondent's race
(trichotomized B/W/H)
(J) Respondent's race
(trichotomized B/W/H)
Mean
Difference (I-
J)
Std. Error
Sig.
BLACK:(1)
WHITE:(2)
-.17509
*
.05487
.004
HISPANIC:(3)
-.03327
.06900
.880
WHITE:(2)
BLACK:(1)
.17509
*
.05487
.004
HISPANIC:(3)
.14182
*
.05321
.021
HISPANIC:(3)
BLACK:(1)
.03327
.06900
.880
WHITE:(2)
-.14182
*
.05321
.021
Multiple Comparisons
Dependent Variable: High School GPA (recoded from "grade")
Tukey HSD
(I) Respondent's race
(trichotomized B/W/H)
(J) Respondent's race
(trichotomized B/W/H)
95% Confidence Interval
Lower
Bound
Upper
Bound
BLACK:(1)
WHITE:(2)
-.3039
-.0463
HISPANIC:(3)
-.1952
.1287
WHITE:(2)
BLACK:(1)
.0463
.3039
HISPANIC:(3)
.0169
.2667
HISPANIC:(3)
BLACK:(1)
-.1287
.1952
WHITE:(2)
-.2667
-.0169
The mean difference is significant at the 0.05 level.
Homogeneous Subsets
High School GPA (recoded from "grade")
Tukey HSD
a,b
Respondent's race
(trichotomized B/W/H)
N
Subset for alpha =
0.05
1
2
BLACK:(1)
166
3.0572
HISPANIC:(3)
179
3.0905
WHITE:(2)
758
3.2323
Sig.
.842
1.000
Means for groups in homogeneous subsets are displayed.
a. Uses Harmonic Mean Sample Size = 232.019.
b. The group sizes are unequal. The harmonic mean of the
group sizes is used. Type I error levels are not guaranteed.
Note
. Adapted from
Data Sets and Codebooks
, by Colorado State University Global, n.d.,
Canvas (
https://csuglobal.instructure.com/courses/81945/modules
) and
[DataSet1]
C:\Users\SnS_M\OneDrive\Desktop\CRJ_575_Analytical Methods\Datasets
Codebooks\mtf11sdss.sav. Data analytics were performed using IBM SPSS statistics for
Windows (Version 28.0)
[Computer Software] by IBM (https://www.ibm.com/products/spss-statistics).
References
Abebe, T. H. (2019). The derivation and choice of appropriate test statistic (z, t, f and Chi-Square
test) in research methodology.
Mathematics Letters
,
5
(3).
https://doi.org/10.11648/j.ml.20190503.11Chen, T., Xu, M., Tu, J., Wang, H., & Niu, X.
(2018). Relationship between omnibus and post-hoc tests: An investigation of
performance of the f test in ANOVA.
Shanghai Archives of Psychiatry
,
30
(1).
https://doi.org/10.11919/j.issn.1002-0829.21801
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Chen, T., Xu, M., Tu, J., Wang, H., & Niu, X. (2018). Relationship between omnibus and post-
hoc tests: An investigation of performance of the f test in ANOVA.
Shanghai Archives of
Psychiatry
,
30
(1). https://doi.org/10.11919/j.issn.1002-0829.21801
Colorado State University Global. (n.d.).
Modules: Data Sets and Codebooks
, Canvas.
https://csuglobal.instructure.com/courses/81945/modules
Haans, A. (2019). “contrast analysis”: A tutorial.
Practical Assessment, Research, and
Evaluation
,
23
(9). https://scholarworks.umass.edu/pare/vol23/iss1/9
IBM. (n.d.). IBM SPSS Statistics for Windows (Version 28.0) [Computer Software].
https://www.ibm.com/products/spss-statistics
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