Derrington 2012 thesis.pdf - Anglia Ruskin Research Online

5.3.4 Sample size and power
The study was designed with the practicalities of a manageable caseload within the
time allocated, rather than powering the study for a particular sample size, at 90% for
example. It was difficult to increase the sample size, and therefore power, due to
these time constraints. However, the ‘observed power’ given by the SPSS model was
still useful, especially when the data were not significant. This gave the strength of
the data to predict the parameter estimates and therefore help ascertain whether a nonsignificant
result was due to a too small sample size and not enough power, or
because there was no real effect from treatment.
The small sample size should not invalidate any findings because the sample was
representative (Denscombe, 2007). However, to increase the Youth at Risk project’s
sample size and power, it is explained in chapter nine how subsequent music therapy
projects anticipate following this same research method and adding to the number of
subjects.
5.3.5 Clinical intervention
Students were offered individual music therapy sessions, once a week for up to 20
sessions with each session lasting 40 minutes. The therapist kept notes after each
session and conversations with teachers, as well as an attendance register noting
reasons for a student’s absence. This meant that there was a record of how many
sessions were offered in total and how many the students attended. It was right to
provide as many sessions as possible in the two terms until the student had attended
up to 20 sessions as it is known from experience that students can miss sessions for
all sorts of reasons.
As described fully in chapter four, the music therapy approach is one which has been
used, developed and been largely informed by experience and practice with teenagers
with various emotional and behavioural problems over the last ten years. The main
intervention methods were active music-making such as improvising and playing precomposed
music, songwriting, and receptive methods, such as listening to CDs of the
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