16. Affirms the need for States to improve the collection and use of quantitative, qualitative and comparable data on violence against women and harmful practices, disaggregated by sex, age, disability, civil status, race, ethnicity, migratory status, geographical location, socioeconomic status, education level and other key factors, as appropriate, to enhance research and dissemination of evidence-based and good practices relating to the prevention and elimination of child, early and forced marriage and to strengthen monitoring and impact assessment of existing policies and programmes as a means of ensuring their effectiveness and implementation;