The site founding index

Three of the measures I use to monitor settlement dynamics have both a spatial and a temporal component. They are described individually below. The first two have no direct relationship to patterns of population growth or decline, being strictly derived from site occupation and abandonment data. The third, however, is a way to monitor changes in population density across the survey area.

The site founding index measures the percentage of sites in a given phase which were not occupied in the preceding phase. Thus:

  
$I_{sf}=100\frac{S_{n}}{S_{n+}S_{p}}$ 




where $I_{sf}$ = site founding index 


		 		 $S_{n}$ = number of sites occupied in phase not occupied in the previous phase 


		 		 $S_{p}$ = number of sites occupied in phase also occupied in the previous phase

Obviously, a high value means that many news sites were founded in a phase, and a low value means few new sites were founded.