CILIP and the Labour Party are quite rightly calling for more transparency on library figures, alongside a more timely rate of publication. As the libraries sector is becoming ever more dependent on the use of volunteers, it would also be a good idea if someone would actually make some attempt to monitor whether "community managed libraries" actually work.
At present, the only evidence is anecdotal, and (in my view) unreliable. I think this is for a number of reasons:
a) Many volunteers don't really understand the scale or scope of what public libraries do, so they tend to overestimate what "their" library does in comparison.
b) Volunteers are normally trying desperately to fund raise and you raise funds by selling what a good job you can/are doing, not by a candid assessment of what is going well and what isn't.
c) Politicians and Councils don't want to get into fights with residents so they aren't completely candid in explaining that the volunteer run services are functioning at a much lower level than the previous Council services.
d) Some of the costs of community run libraries can be quite hidden compared to local government figures. For example, there can be ongoing managerial support from the Council, "grace and favour" arrangements for the use of buildings, use of Council IT systems with less than transparent charges and so on.
e) Some of the outcomes of community managed libraries can also be untested. For instance, I don't think most such libraries formally measure loans and visits in the way CIPFA expects or have any equivalent to the PLUS surveys. If they have monitoring systems, I suspect they are probably quite specific to each institution and therefore it is hard to draw comparisons.