17.1 The focus of this chapter is on two important aspects of data quality assessment—serviceability and accessibility—and on their applicability to the external sector statistics. Serviceability of statistics refers to the extent to which datasets are kept in good working condition to be able to serve various users’ needs effectively. Accessibility refers to the extent to which statistics are made available to users in a clear and understandable manner; the adequacy of the forms of dissemination; the level of restriction in accessing the data; the extent to which pertinent metadata are made available and kept up-to-date; and the availability and promptness of support to data users. Serviceability and accessibility are two of the five dimensions of the IMF data quality assessment framework (DQAF), the Fund’s organizing model of the Report on the Observance of Standards and Codes (Data ROSC). Other dimensions of data quality are assurance of data integrity, methodological soundness, accuracy and reliability, along with the prerequisites of quality that relate to institutional aspects (see Box 17.1). These attributes of data quality are applicable in the assessment of external sector statistics.