Demographics
When we look at crime counts at different spatial scales, it is often useful to try to understand the demographics of the area. Older people are more likely to be victims of certain crimes, for instance, and for others there are often correlations between crime incidence and the deprivation, socioeconomic status or other makeup of the area.
The UK census is the biggest source of demographic data, providing many attributes over various spatial scales. With census data there is always a tradeoff between spatial and categorical resolutions, often to preserve anonymity. For example, the highest spatial resolution for counts of people by age in years is MSOA, and at higher resolutions (LSOA, OA) age is only given in 5-year bands.
Another very important consideration is that we will want to aggregate people to non-statistical geographies, such as grids and hexes. In order to do this, we could simply place people at random points within the statistical geography, then take those that fall within the new geography. However this can be unrealistic, particularly in areas that are rural or contain large-scale non-residential infrastructure or bodies of water (despite Monty Python's boasts, nobody in Yorkshire lives under a lake!).