Notes on the Dataset

English Slave Trade, 1791-1799 (House of Lords Survey)
Known Problems with the Data

These House of Lords Records were in a confused and imperfect state. Subtracting those slaves who died on the coast, were landed again or trans-shipped, from the total number of all slaves purchased (var. 9), often does not equal the final number of slaves who did ship out from Africa (var. 16). Equally, the number leaving Africa, less those who died at sea in the Middle Passage often does not equal the number of slaves listed as having been landed. Depending on the needs of the research, these cases can either be ignored or eliminated entirely. Equally, sometimes the age and sex breakdowns are given for a given var., and sometimes only the total. There is also the unique case of var. 9 which sometimes gives a new category of total men and women instead of the sex-age breakdown usually provided. But this total category is never carried through to the other succeeding vars and thus causes confusion.

A last problem has to do with the large number of ships for which missing data occurs. Often the number who died at sea is known, plus the number who landed, but the number shipped is not given. One can reconstruct the shipped by adding died at sea and arrived. Equally when arrived not given, then shipped less died at sea will give the figure. There are a suspiciously large number of ships which show no mortality in the Middle Passage despite extremely lengthy voyages. I personally eliminated these. There were also date recording errors in the original, plus a confusing use of ditto when I believe the material was not equal to the previous data (this was especially the case with months and ports). In short, this is an extremely chancy dataset which I do not consider to be very reliable.

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