With Allan Heskin and Mark Garrett, we examined the effects of vacancy control over rental units on 1980-90 changes in housing and demographic characteristics. Comparing the border areas of four California cities with vacancy control (Santa Monica, Berkeley, West Hollywood, and East Palo Alto) with the borders areas of the adjacent cities, we were able to show that vacancy control policies have had little effect on the demographic composition of tenants over the 1980-90 period, but that they have affected the tenure status of rental housing. In the vacancy control cities, there were fewer new rental housing units created during the decade, but more ownership units. We have hypothesized that many rental units were converted to ownership units during the period.
Here is a map from the study.