Derrington 2012 thesis.pdf - Anglia Ruskin Research Online

Parametric tests are statistical tests of significance to infer differences and
relationships between numerical data variables (Brown and Saunders, 2008). They
require certain assumptions for the statistics to be accurate and reliable, including the
assumption of normally distributed data and the homogeneity of variance. The
homogeneity of variance is the assumption that variants should be the same
throughout the data and the variability within the two groups is similar enough (Field,
2009). This assumption, using Levene’s test (1960), tested the null hypothesis that the
variances in the different groups were equal 39 . The lack of fit was used to check that
the model fitted the data and the residual plot used all the variables in the model,
predicted the estimates and presented what was left over 40 . These tests were used in
all the inferential statistical analyses.
Descriptive statistics were carried out for the analysis of the secondary data from the
teachers’ questionnaires, then inferential statistics using a MANOVA were
calculated. To determine any lasting effect of music therapy, short-term follow-up
data were analysed (5.2).
The music therapy project questionnaire, which addressed students’ feelings and
attitudes about school and anger, was examined differently. The results for the three
anger statements were separated from the twelve statements about school in the
descriptive statistics. They were then tested using logistic regression in order to
analyse the proportions. The Hosmer-Lemeshow test was set by SPSS and used as the
goodness of fit for this analysis.
5.8.1 Multiplicity
The issue of multiplicity, which means having several endpoints of interest, led to the
decision to do a combined analysis of the key endpoints in a multivariate analysis of
variance (MANOVA). The benefit of combining the three Beck endpoints (BSCI,
BAI and BDBI) into a single analysis meant that the 5% alpha level did not have to
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$* !If the Levene’s test is significant, and therefore less than 0.5, the variances are
significantly different in different groups and homogeneity of variance cannot be
assumed. !
%+ !If there is a pattern to this residual plot it shows an error in the method because the
residual plot should be random if the method is good.!
! "#'!