I agree with Anna. Cost per use is not straightforward to calculate because of different PDA models. Do you compare cost per use over a given period or the lifetime of e-books owned by the library?
We are in our second year of PDA at Bangor and have some ballpark figures to prove that titles purchased through PDA are used more often than non-PDA titles.
Average number of unique accesses (2010-11)
PDA titles : 16.3
non-PDA titles : 4.8
Given that we pay for 3 'short term rentals' before purchasing any title through PDA, the actual cost of PDA titles is higher than non-PDA titles. However, even if you add the cost of 3 rentals at an average of 30% of the list price, these figures prove the average cost per use of PDA titles is still lower than non-PDA titles. Also if the same trend continues and PDA titles are used more often in subsequent years 'cost per use' will be even lower over a longer period.
Calculating the cost of PDA is certainly a complex but increasingly important area which needs further investigation. If you are responsible for collecting SCONUL statistics how do you account for your 'short term rental' charges? Do they come under e-book purchases or document delivery? In the current year the average cost of our 'short term rentals' so far is £5.44. If you include free browsing periods the actual cost is even lower. At present these charges are treated as e-book purchases making e-books we actually purchase seem more expensive than they are.
So many questions, not many answers.
Mieko
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Mieko Yamaguchi [log in to unmask]
Head of Collection Management Phone: +44 (0)1248 382970
Bangor University Library Fax: +44 (0)1248 382979
