Page 87 - Physical activity in recipients of solid organ transplantation - Edwin J. van Adrichem

‘acceptable’; and > .80 as ‘good’.
determine statistically signi
Physical activity in recipients of solid organ transplantation
included in the analyses. Descriptive statistics were used to report participant
characteristics. To re-evaluate the internal consistency of the questionnaire in the current
sample, the Cronbach’s
alpha
Cronbach’s
alpha
was calculated for the overall barrier and motivator scales.
measures the degree of consistency according to the two-way intra class
correlation coe

cient.
15
Additional analyses were performed to investigate possible
improvement of overall Cronbach’s
alpha
if individual items were deleted.
To explore the underlying component structure, an explorative principal component
analysis was performed and subsequently followed by an oblique rotation according to the
direct oblimin criterion to facilitate the interpretation of the components. Con
distinguish loadings that are signi
cantly di

erent from zero from those who are not.

dence
intervals (CI) of the component loadings were determined by bootstrapping in order to

e
number of unrotated components to be retained was determined according to the
minimum generalized cross-validation criterion.
17
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Generalized cross-validation is a model
validation technique that indicates the optimal number of components to be retained in
order to account for most of the data variability. Eigen values and corresponding
cumulative variances explained by the retained components were calculated. Items with a
signi

cant loading greater than 0.3 in absolute value were classi
component, a procedure resulting in subscales.

ed as belonging to a

e consistency of the implied subscales was
determined by Cronbach’s
alpha
, and its 95% CI. Cronbach’s
alpha
coe

cients <.50 were
interpreted as ‘unacceptable’; .50 to .60 as ‘poor’; .60 to .70 as ‘questionable’; .70 to .80 as
Additionally, a series of regression analyses (ANCOVA) were conducted to

cant di

erences between the organ transplantation groups on
each of the barrier and motivator components while controlling for age and gender of the
recipient.
85.
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