achievement of durable solutions, births and deaths) so that data on the size and composition of refugee populations can quickly become outdated; and (d) data protection and privacy issues.

# **_IDPs_**

Data on IDPs are compiled, analyzed and disseminated by a number of organizations, including IDMC, UNHCR,<sup>89</sup> OCHA, ICRC, WFP, IOM, JIPS, as well as NGOs and research institutes. IDMC is the lead organization responsible for aggregating sources and establishing estimates of new and cumulative displacements that are as reliable as possible. IDMC relies on a wide range of secondary sources of information, including national governments, international organizations, national and international NGOs, human rights organizations, the media and IDPs themselves (IDMC 2015). It publishes estimates of internal displacement caused by conflict, generalized violence, and human rights violations in over 60 countries.

IDMC candidly acknowledges the challenges associated with data compilation and the corresponding limitations in terms of the completeness, quality, reliability and comparability of aggregate numbers. IDMC’s aggregation and analysis is constrained by the scope and quality of its source data. Significant challenges include:

- (a) The lack of consistent definitions and methodologies (across locations and over time), in particular the lack of consensus on when internal displacement ends (IDMC 2015). Consequently, data may be aggregated across situations and countries even though the source data were generated for different purposes and using different methodologies.

- (b) Very few national governments collect or report up-to-date data on IDPs. Political will as well as the resources and capacities to carry out effective and timely data collection vary across countries. In 2015, only five governments responded to IDMC requests for data.<sup>90</sup> Consequently, data on internal displacement is outdated in several countries and is at risk of becoming outdated in others, including countries like Afghanistan with large IDP populations (IDMC 2016).<sup>91</sup> Problems of outdated and ‘decaying’ data are especially problematic in protracted displacement situations—international organizations reallocate resources to more visible or pressing displacement crises (IDMC 2016).

- (c) Limited official standards and guidance on how to collect data on IDPs in the field. IDMC may rely on more than one source in some countries (each gathering data for different purposes and using different definitions and methodologies with little or no coordination) and so double counting and gaps cannot be excluded (IDMC 2015). IDMC reported that changes in the way their sources collect and analyze their data led to dramatic adjustments in 2014 figures, e.g. in Côte d’Ivoire a profiling exercise led to a four-fold increase in IDMC’s estimate, and in Nigeria improvements in the national capacity to collect information led to a 70 percent decrease in IDMC’s estimate (IDMC 2015).

- (d) The lack of complete data for most countries. The fluidity of population movements, insecurity and other access restrictions (lack of transport infrastructure, high logistical costs and government restrictions) make primary data collection almost impossible in many areas (IDMC 2015). Consequently, data collectors often focus on IDPs in relatively stable, secure and accessible places (e.g. camps) and estimations in the most difficult areas rely on ‘local informers’ (e.g. local authorities, NGOs etc.) who may or may not have the capacity to provide adequate numbers, or which leaves data collection and reporting subject to the influence of parties to the conflict (IDMC 2016). Figures do not always capture ‘invisible’ IDPs that are living in individual accommodation dispersed in host communities, and therefore figures are

> 89 The statistics of UNHCR on IDPs are limited to countries (numbering 24 in 2013) where the organization is engaged in assisting or protecting IDPs.

> 90 Azerbaijan, Bosnia and Herzegovina, Georgia, Ireland and Mexico (IDMC 2016)

> 91 IDMC notes that outdated or ‘decaying’ data are a problem in 12 of the 53 conflict- or violence-affected countries it monitors (Armenia, Bangladesh, Congo, Cyprus, Guatemala, Macedonia, Nepal, Papua New Guinea, Thailand, Togo, Turkey and Uganda), accounting for approximately 20 percent of IDPs worldwide (IDMC 2016).