Good quality modelling and evaluation is hampered by challenges in sharing data and a lack of common data standards. Government does not always see data as a priority and data quality is often inadequate. We have drawn attention to poor data and a lack of joined up systems in numerous reports over the years, such as on supporting the vulnerable during lockdown, on tackling the tax gap, on effective regulation of gambling, on dealing with rough sleepers, and on identifying and tackling fraud and error. When producing and using models, poor data can lead to additional time and increased difficulty when quality assuring the model inputs. This difficulty is compounded by a lack of data standards across government which means there are inconsistent ways of recording the same information. When dealing with new situations, such as the rapidly changing pandemic, Government needs to be fast and agile at sharing data. Recommendation: The Cabinet Office should set out its progress in using its national data strategy to address the barriers to better sharing and use of data, including its development of cross-government standards for collecting, storing, recording and managing data.