Data can often be obscure with shorthand column labels or even just fiels 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 daily 'temp' field means minimum, maximum or average temperature. The latter, (ii) the provenace of the data is critical if oters are to know whether it is reliable. Amongst other thinsg this is essential to be aware of possible bias in the dataset.
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