Biostatistics and Informatics: ANCOVA Analysis, Odds Ratio, and Association

Biostatistics and informatics
Biostatistics and informatics
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Biostatistics and informatics
Question One
ANCOVA analysis for differences in MAXFWT by GROUP while controlling age and sex
The following tables show the results of the analysis.
Table 1
Descriptive Statistics
Dependent Variable: MAXFWT
GROUP Mean Std.
Deviation
N
1 54.44 12.057 64
2 44.00 12.654 19
3 51.50 12.946 16
Total 51.96 12.839 99
The table’s information reveals that the groups’ mean MAXFWT are differing while variance
lies within the same range
Table 2
Levene's Test of Equality of Error Variances
Dependent Variable: MAXFWT
F df1 df2 Sig.
.482 2 96 .619
Tests the null hypothesis that the error variance of
the dependent variable is equal across groups.
a. Design: Intercept + GROUP + sex + age
From the table above the P-value (0.619) is greater than 0.05 significant levels. This reveals that
there is no significant difference between the variances of MAXFWT of different groups

Biostatistics and informatics
Table 3
Tests of Between-Subjects Effects
Dependent Variable: MAXFWT
Source Type III Sum
of Squares
df Mean Square F Sig.
Corrected Model 7682.804a 4 1920.701 21.313 .000
Intercept 3885.492 1 3885.492 43.116 .000
GROUP 836.852 2 418.426 4.643 .012
sex 79.543 1 79.543 .883 .350
age 6047.920 1 6047.920 67.112 .000
Error 8471.035 94 90.117
Total 283434.000 99
Corrected Total 16153.838 98
a. R Squared = .476 (Adjusted R Squared = .453)
While age and sex control the MAXFWT between groups differ from each other, this has been
revealed by P-value (0.012) groups which is less than 0.05 significant levels.
Estimated Marginal Mean by Groups
Table 4
Dependent Variable: MAXFWT
GROUP Mean Std. Error 95% Confidence Interval
Lower Bound Upper Bound
1 53.701a 1.190 51.337 56.064
2 46.053a 2.198 41.689 50.416
3 52.010a 2.375 47.294 56.726
a. Covariates appearing in the model are evaluated at the
following values: age = 10.073232, sex = 1.40.
The information in the table above reveals that the model estimated statistics of MAXFWT are
different from its observed values statistics. This is evident when table 1 is compared with table
4.