Marina Wyss explains various techniques for handling missing data in data sets:
Missing or incomplete data can have a huge negative impact on any data science project. This is particularly relevant for companies in the early stages of developing solid data collection and management systems.
While the best solution for missing data is to avoid it in the first place by developing good data-collection and stewardship policies, often we have to make due with what’s available.
This blog covers the different kinds of missing data, and what we can do about missing data once we know what we’re dealing with. These strategies range from simple – for example, choosing models that handle missings automatically, or simply deleting problematic observations – to (probably superior) methods for estimating what those missing values may be, otherwise known as imputation.
I like the distinction in form Marina draws, and we also get a good set of techniques for filling the gaps.