Milyen adataink vannak, milyenek lehetnének?

The paper gives an overview of new developments in library evaluation, focusing on those methods that have been defined in international standards. Based on current changes in the tasks and activities of libraries, library statistics have to admit new definitions and data collection methods. The same happens in performance or quality measurement, where the indicators have to be adapted to new developments in libraries and in the information world. Statistics show the quantity of input and output in libraries; performance measures assess the library's products and services in terms of user-orientation, speed, accuracy, reliability, or efficiency. But today there is a general demand on public institutions to prove their value for society. For libraries this means providing evidence that people benefit when using a library. Impact or outcome assessment tries to identify the effect of library services on users and on society. Methods for such assessment will be described in a new ISO standard. (Original abstract) [ABSTRACT FROM AUTHOR]