Balance of baseline characteristics is particularly important to establish for cluster trials given the (higher level) unit of randomisation.
Note that a multi-level analysis approach could have been applied to these data, as the young people attending centres are clustered within the higher level unit of the different centres that they attended [ 21].
Preliminary analyses, however, revealed no clear trends at the higher level unit of the 55 centres and, as this factor was not relevant to the current hypotheses, this analysis approach was not undertaken.
Also, all equations would be estimated with the cluster option in STATA to adjust standard errors for intragroup correlation, and the cluster identifier was the highest level units of the model (i.e., hospital/clinic).
It clearly points out the failed assumption that the history of components is congruent with the history of the higher level unit to which it belongs.
However, statistical techniques for correcting for the effects of clustering tend to be overly severe and conservative 23 when a small number of higher level units (clusters) are used, and therefore we tested whether the clinics were in fact significantly different from each other.
There is a need for data that allow the analysis of individuals and higher level units simultaneously, preferably over time.
Some of the confusion and conflict over higher-level units of selection arose because of an historical contingency Wynne-Edwards' implicontingency Wynne-Edwardsof selectimplicitthe responses it provokedefinitionof2010).
Contextual effects refer to the influence a neighborhood or other type of higher level unit has on people, while compositional effects are simply reflective of the characteristics of individuals comprised by the neighborhood or other setting.
It considers high level units (systems) of habitats that rarely considered in other habitats classification attempts as mentioned by Franklin (1993) and Noss (1996) and it avoids to classify habitats based only on vegetation types or/and species communities such the work done by Kirkpatrick & Brown (1994); Faith and Walker (1996a) and Kassas (1999).
It has been argued that this is due to an early activation of high-level units in the ventral visual stream – these units are assumed to select high-level feature conjunctions diagnostic for target-category stimuli [13].
