DClinPsy Portfolio Volume 1 of 3 - University of Hertfordshire ...

Sample size:
To ensure adequate statistical power to detect a moderate correlation, a power analysis
was carried out using G Power. The power analysis conducted suggested that a sample
size of 64 would be sufficient to detect a moderate correlation r= 0.30 with power at 0.80
and at alpha at 0.05 (1 tailed). The total sample used was ninety-six.
Procedure:
Recruitment
The researcher approached seven secondary schools in London to ask for participants for
this study. Four schools agreed to take part and one school agreed but did not have any
consent forms returned so was not involved further in the study, the other two schools
refused to participate stating no reason. The schools were sent ‘information sheets for
teachers’ electronically (Appendix 6). Those schools that accepted the invitation to be a
part of this study were given copies of information sheets for parents, a cover letter with
details of the deadline for returning the consent form for each adolescent’s parents and a
consent form that was to be signed by a parent or guardian (see appendices 6, 7, 8
respectively) for each adolescent. These documents were to be sent out to the
parents/guardians of all 12-16 year old females able to complete the questionnaires on the
pre-determined days. A convenient time was arranged for the researcher to attend each
school in order to collect the data.
At each school the researcher distributed the measures and asked the adolescent girls to
complete all the questions on all the questionnaires quietly. Information about the
researcher and purpose of the study was given in brief. The participants were also asked
to take it in turns to be weighed and measured by the researcher using scales and a ruler.
They were to go to a discrete corner of the classroom or dining hall to be weighed and
measured in confidence, one at a time.
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