The corporation "does not have a clear view of the total budget for coverage of individual major music and sporting events" like Glastonbury and Wimbledon because there are so many "media platforms" involved, according to a report by the National Audit Office (NAO).
It also fails to carry out any kind of cost-benefit consideration of a range of coverage options, making it difficult to assess the success of its coverage and ROI.
A total of £357m was spent on the rights for and coverage of sporting and music events in the 2008-09 financial year.
The report singled out the BBC's construction of a £250,000 studio in Vienna for the Euro 2008 football championships because the one allocated was four miles from the centre and didn't have a view of the city's skyline.
"Millions of people enjoy the coverage of major sporting and music events provided by the BBC. But, particularly given the current economic conditions, the BBC has not done enough to demonstrate that its coverage provides the best possible value for money," said head of the National Audit Office, Amyas Morse.
"When the BBC decides that it wants to cover a major sporting or music event, it should carefully explore a range of options, and set down clear objectives against which it can measure its achievements after the event. Without that, the BBC will not convince licence fee payers that their money has been well spent."
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