Time-series data on British annexations come from the compendium by Stewart (1996). This lists every territory annexed by Britain since 1493 with the initial date of annexation. It also provides brief historical information on each territory. This data is more robust than the data from Henige (1970) that has been typically used in world-system analyses of colonization. Henige lists colonial governors appointed by all states. Scholars have used the data as a rough measure of the year when a new colony was annexed, corresponding with the year when the first colonial governor was appointed. The shortcoming is that the data does not differentiate between territories that are newly acquired and territories that are renamed or reorganized. Alternatively, Stewart's book enables us to ascertain the year when Britain first annexed a territory and thus treat it as a single event. Stewart's book provides the name of each territory and year of founding while providing a brief historical overview. The overview enables the analyst to ascertain whether the territory had been previously colonized by Britain or not. If it had been, it would not be counted in the data as a new colonial annexation. Conversely, Henige's data would include when a colony that has already been taken is simply reorganized or renamed.

Data on British military interventions are compiled from the following sources: (Clowes 1903), (Farmer 1984[1901]), (Harris 1944), (Kohler 1975), and Public Record Office files (ADM 171–1, “Naval General Service Medal 1793–1840”; ADM 171/202: “Naval Medals and Clasps Awarded from 1818 to 1914”). Information from these sources is necessary for supplementing information in traditional war databases such as the Correlates of War data in Singer (1987), which only lists large-scale interstate wars. Because of data limitations, the data begins in 1800 only. “Military intervention” includes small wars, big wars, and troop or naval deployments. Small operations involving slave raiding or infrastructural building are not included. The data is coded to specify the year the intervention began. Each intervention is treated as a single event, so repeated deployments of troops for the same engagement are not added; only the initiation of the event is entered.