Nielsen purchases scanner data from retail transactions to track the sales of consumer packaged goods, gathered at the point of sale in retail stores of all types and sizes. Scanner data is an example of:

syndicated external data.

Explanation: This brings us to the definition of syndicated data :-

Syndicated data refers to general market data that is not specific to any particular client, rather a compilation of retailer and product data, syndicated data is generally collected by market research firms and then bought by businesses who have developed interest in the market.

answer; availability;