What is the collection I’m looking at?

In carrying out a search in any collection we need to first interrogate what it is, understand what it holds, and equally importantly, what it does not. For example, is the record that we are looking at a first-hand account of the event we are interested in? Most census records that we use, for example, are not ‘primary’ records – they are ‘secondary’ copies made by enumerators from original schedules filled in by heads of households, which in most cases have been subsequently destroyed. The very act of copying a source can introduce errors into the quality of the record we are using, or deliberate changes to cater for statistical categories of information, such as occupations.