Notes on using Jamaican inventories

The text below is taken from Trevor Burnard, Planters, Merchants, and Slaves. Plantation Societies in British America, 1650-1820 (Chicago and London, University of Chicago Press, 2015), Appendix. ‘An Essay on Sources’ (pp. 274-75). We are very grateful to Prof. Burnard for permission to reproduce the text here.
In the appendix Trevor Burnard gives a brief explanation of a major source for his book, a database of all inventories recorded in Jamaica between 1674 and 1784, contained in the Jamaica Archives, Spanish Town, Jamaica, IB/11/3/1-65, JA:

Four volumes, dating from the 1690s and 1700s, are missing, and one, from 1760, is unreadable. I have abstracted from the remaining sixty volumes 10,222 separate individual inventories, occasionally combining inventories when it is clear that the inventories concerned relate to the same individual. Each person was given a separate file and was noted by name, occupation, parish, and total estate value. For each inventory I abstracted the number and value of enslaved people, noting whether they were male or female and determining, when appraisers gave this information (which they did sometimes) whether the slaves were men, women, boys, girls, or children. I also counted cash, plate, and jewelry to get an idea of monetary assets and summed debts owed to each estate. The total value of the estate was recorded and converted into sterling values. I also determined what percentage of total estate value was made up of slaves and what percentage was of debts.
An inventory was a list of belongings of the deceased as appraised by two men, usually neighbors, under the direction of the executors of the estate. It was not a simple task to appraise estates, especially large ones, since each item of personal property had to be listed and assigned a value. The very largest estates resulted in inventories running over ten pages. Because the task was burdensome and required considerable precision, men sometimes tried to avoid being an appraiser. Nevertheless, appraising one's fellow estate was a crucial civic duty. Most appraisers took their job seriously. The evaluations in estates are remarkably detailed and are very accurate about prices assigned to goods. Occasionally inventories describe auctions, where we can presume that the prices recorded were the prices actually paid. A comparison of inventory values and prices received at auctions indicates that inventory values were 2 percent higher than auction sales. Given that many auctions were probably conducted for estates in distress, such a gap in prices is trivial and suggests that inventoried prices are accurate guides to values in Jamaica.
Nevertheless, inventories have biases. Some things are enumerated better than others. The coverage of enslaved people is especially good. Appraisers counted all slaves and assigned values to slaves, usually, in the eighteenth century, as individuals. The variation in prices between individual enslaved people and the close connection between slave price values in inventories and slave price values in auctions suggest that appraisers valued individual slaves accurately. They were less careful about debts. One drawback of Jamaican probate records is that, unlike Maryland probate records, they do not include a calculation of debts owed by the deceased, meaning that gross but not net wealth can be calculated. Not all debts were enumerated in inventories even when it is likely that many people were lending out money. There were 131 decedents, 7 of whom were Kingston merchants, who left estates worth more than £5,000 without debts listed. There were in total 4,440 decedents who did not have debts listed. The likelihood is that appraisers did not always know what debts were owed and thus omitted them. Thus, there is probably a bias toward undercounting the wealth of planters. It is also probable that merchants' wealth is overstated in other ways. Many appraisers made detailed lists of all merchants' stock in trade. While such enumeration is a godsend for the historian of consumption, it does mean that the shop goods of merchants are counted in their estate as if they were actual possessions instead of items held in shops.