Information Technology Reference
In-Depth Information
Box's Test of Equality of Covariance Matrices
a
Box's M
F
df1
df2
Sig.
7.961
1.005
6
3.589E3
.420
Tests the null hypothesis that the observed covariance matrices of the dependent
variables are equal across groups.
a. Design: Intercept
+
age
+
gender
+
age * gender
Within Subjects Design: attract
Figure 14.11
Box's test results.
14.6 SPSS OUTPUT OF THE OMNIBUS ANALYSIS
The results of Box's test, shown in Figure 14.11, is not statistically signif-
icant; this indicates that the assumption of the equality of the covariance
matrices cannot be rejected. Mauchly's Test of Sphericity, the results of
which are shown in Figure 14.12, cannot be performed with only two levels
of the within-subjects variable. Levene's test of error variance equality was
not statistically significant (see Figure 14.13); we therefore cannot reject
the assumption of homogeneity of variance.
The within-subjects summary table is presented in Figure 14.14. All
of the effects except for the Attract
Age interaction are statistically sig-
nificant. The three-way interaction of Attract
×
Gender is signif-
icant: We know that the combinations of all three independent variables
affect performance on the dependent variable. Because this is highest
order interaction, this is where we need to concentrate our simple effects
analyses.
×
Age
×
Mauchly's Test assesses equality of
group variances and correlations. Because
there is only one correlation, it cannot be
compared to any other. Therefore, the
sphericity assumption cannot be tested.
This is why there is zero df and why there
is no computed probability (Sig.).
Mauchly's Test of Sphericity
b
Measure:MEASURE_1
Epsilon
a
Within
Subjects
Effect
attract
Approx. Chi-
Square
Greenhouse-
Geisser
Mauchly's W
df
Sig.
Huynh-Feldt
Lower-bound
1.000
.000
0
1.000
1.000
1.000
Tests the null hypothesis that the error covariance matrix of the orthonormalized transformed dependent
variables is proportional to an identity matrix.
a. May be used to adjust the degrees of freedom for the averaged test of significance. Corrected test are
displayed in the Test of Within-Subjects Effects table.
b. Design: Intercept
+
age
+
gender
+
age * gender
Within Subjects Design: attract
Figure 14.12
Results of Mauchly's sphericity test.
