Typical research that is concentrate on specific location. Bounds of research are constrained in order to allow for greater focus. Multi site research focuses on more than one such site. Multi site research holds greater potential for comparison, single site research holds potential for comparative research b focusing on within rather than between case variations. Single site research can also be used to provide empirical tests of theories. Single site research allows for a detailed analysis of the sequencing of events that resulted in a particular outcome- a technique known as process tracing- which can lead to insights into causal mechanisms, aiding in theory-building. Most easily understood as a multi site research design comparable to mill"s method of. Begin by selecting cases that are very different in many respects but where the phenomenon being investigated always occurs (i. e. there is agreement in the outcome) Comparisons between the cases can eliminate factors that are unnecessary for the phenomenon to occur.