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

Limitations of study
Cross sectional study design:
This study employed a cross sectional design which offers a snap-shot of a sample at a
particular time and therefore cannot offer a longer-term perspective or conclude on
causative or maintaining factors.
Difficulties with BMI measurement in growing adolescents:
While BMI has a high correlation with relative fatness or leaness it is assessing the
weight to height relationship which may give misleading results in girls who are very
muscular and who might therefore appear obese on the BMI alone. When diagnosing for
clinical purposes further assessments can be carried out to determine if excess fat is a
problem (such as skinfold thickness measurements, evaluations of diet, physical activity
and family history). Such a detailed assessment was not carried out for the purposes of
this study.
A further issue as regards the BMI was categorising the BMI values from this sample
using the USA as opposed the UK percentile groups. The UK percentile groups were
more stringent than those of the US and consequently fewer participants fitted the
categories. The US categorisation enabled better comparison of the groups but was used
on a UK sample, which perhaps is not ideal.
Additional limitations:
Due to the focus of the study cultural and gender differences were not adequately
considered. Ethnicities were simply classified under the generic label that denoted their
membership in a racial group. More important information that may have promoted
further understanding of the existence or non-existence, development, and course of
eating disorders among minority groups was not sought.
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