Data can often be obscure with shorthand column labels or even just files full of numbers. It is important therefore to document data, to explain (i) what is there and (ii) how it was obtained. The former (i) is essential if others are to be able to use the data in sensible ways – for example knowing whether a daily 'temp' field means minimum, maximum or average temperature. The latter, (ii) the provenace of the data is critical if others are to know whether it is reliable. Amongst other things this is essential to be aware of possible bias in the dataset.
Used in Chap. 10: page 143