The Ownership Change Database (OCD) contains data for all manufacturing plants that changed their firm identification numbers at least once during the period 1963-2002. Because each plant in the OCD and Census of Manufactures (CMF) is assigned a unique permanent plant number (PPN), researchers can use this number to merge the OCD with the CMF. In this way, data on many other variables available in the CMF - describing economic activities of the plants that changed owners as well as those that did not experience any ownership change (the control group) -- may be obtained for research. The OCD contains data for pairs of Census of Manufactures (CMF) years. For example, the ocd19721977 file contains data for 1972 and 1977, NOT 1973-1976. There is no data in the OCD for non-CMF years.
This product has been discontinued - 2002 is the final year.
