CHAPTER 3 DATA COLLECTION AND ANALYSIS At the same time, data sharing should not be interpreted as granting unrestricted access to information to any interested entity. Ensuring confidentiality of certain categories of data (e.g. data on health or migration status) is indispensable for obtaining real, trustworthy information and respecting the dignity and safety of the child. For instance, a child willing to enter a public education system should not be afraid that the undocumented migration status will be reported to the immigration authorities and, consequently, lead to detention.35 Data sharing is closely linked to the re-use of data. Data obtained on one occasion may turn out to be valuable for other purposes, e.g. data on the children placed in drug treatment institutions may be useful for designing anti-drug policies, developing treatment programmes for drug-addicted children detained in other types of institutions, training professionals or simply further research. Although the secondary use of data can deviate from the purpose of the original data collection, it should be always preceded by ethical assessments and applied in accordance with the principle of ‘doing no harm’.36 The data should not be reused for purposes that adversely affect human rights such as the cooperation of public health administration and immigration enforcement (e.g. as in the case of the United Kingdom37). Data sharing is a culmination of a simplified data cycle (see Figure 2) that will become increasingly important in the digital era. The ease with which data can now be recorded, stored and transferred means that the data collection should not be perceived as a recordkeeping exercise for internal purposes of particular agencies, but as an element of a national data ecosystem, in which common efforts of various actors lead to better policymaking, monitoring of existing policies and responsiveness of State agencies. At the same time, reaching the end of the data cycle by sharing information means that other actors enter their own cycle, starting from phase II (data storage) or phase III (data analysis) and are therefore required to fulfil relevant obligations. 35 CMW-Committee, Concluding observations: Mexico, CMW/C/MEX/CO/3, 2017, para. 54. 36 OHCHR (2018), op. cit., p. 11. 37 Anna Sexton, Elizabeth Shepherd, Oliver Duke-Williams & Alexandra Eveleigh, ‘A balance of trust in the use of Government administrative data’, Archival Science, Vol. 17(4), 2017, pp. 305–330. 50