III. RESULTS
During phase I, the literature review, in 137 of the 290
literature sources elements in relation to strategy were
identified. This means that in almost half of the studies
sources (47.2%) strategy was found to be important in creating
and sustaining an HPO. These elements were grouped in 13
characteristics, which are given in Table 1. From these 13
characteristics, six surpassed the threshold of nine percent
weighted importance and were included in the empirical study
performed in phase 2. These six characteristics are described
underneath, which some selected references (originating from
A studies).