Census data is provided within small area boundaries. Crime statistics are available within police precincts. There is no hierarchical relationship between the two. This means that you can't answer questions such as: how many crimes per capita in a particular precinct/ward. This data estimates the proportion of a precinct that lies within a small area.
You can find the inverse mapping here: https://data.code4sa.org/Government/Small-area-to-police-precinct-weights/aurg-34mw/data
If a small area is not wholly contained within the precinct, a weight is created proportional to the amount of overlap with the precinct. This estimate assumes a linear distribution of people across the entire small area. This assumption may not be correct in certain small areas so use the data with caution.
The value of the small area column refers to the StatsSA SAL number. The value in the precinct column refers to the data as per the crime statistics.
The SAL boundaries used are the 2011 boundaries. The precinct boundaries were obtained in 2016. It is not clear how often these boundaries change and whether SAPS maintains versioning information.