this way, profiling of IDP situations aims to underpin advocacy, protection and assistance activities as well as support the achievement of durable solutions by informing joint strategies between government, humanitarian and development actors.

Profiling provides an overview of displacement-affected populations through the collection and analysis of minimum core data (number of IDPs, disaggregated by location, age and sex) and where possible additional quantitative and qualitative data (causes of displacement, patterns of displacement, protection concerns, humanitarian needs, vulnerabilities, and aspirations and prospects for durable solutions). Profiling may utilize data collection techniques at individual, household and community levels, often combining population estimation methods, a review of secondary data, focus group discussions, household surveys and key informant interviews targeted specifically at forcibly displaced populations (UNSD 2014).<sup>70</sup> Profiling methods focus on displacement situations, rather than only on displaced populations, and therefore includes comparisons to conditions in the host population. IDMC estimates that humanitarian profiling data forms the basis for 18 of their 60 country estimates and around 63 percent of their annual estimates (IDMC 2015), with the largest volume of data on conflict-induced internal displacement provided by OCHA followed by IOM.

There are several practical challenges associated with IDP profiling exercises in displacement situations. Insecurity or terrain may impede access to displaced populations in conflict-affected or hard to reach areas. For example, profiling exercises in Pakistan do not cover all IDPs or areas affected by displacement due to insecurity, and in Afghanistan profiling of IDPs by UNHCR underestimates the scale of the initial displacement as IDPs are only interviewed once displacement sites are accessible, if they are profiled at all (IDMC 2015). Additional challenges include unwillingness of IDPs to participate due to fear of persecution, and mobile populations (IDMC 2008). There may also be political pressures to inflate or reduce numbers.

# **_Population movement tracking systems_**

In situations where the movement of displaced populations is fluid or continuous, a movement tracking system can be a useful tool for providing rough estimates of population flows, including recurrent displacements. Movement tracking systems are useful for monitoring fluid population movements (including spontaneous and organized, internal and cross-border, and returns and resettlement) in remote or inaccessible routes and locations (including displacement sites, places of origin, and places of return and resettlement). UNHCR, IOM and other organizations have developed methods for tracking and monitoring movements of IDPs in over 30 countries, particularly in cases of disaster-induced displacement, but also in some cases of conflict-induced displacement (UNSD 2014). These systems employ a combination of data collection techniques including key respondent interviews, focus group discussions, registration, observations and physical counts, samplings and other statistical methodologies. For examples, UNHCR’s population tracking systems identifies and trains local NGOs to monitor key locations such as IDP settlements, bus stations and roads to report on movements.

The accuracy of data from movement tracking systems is subject to several caveats. These include: limited access to locations and routes due to insecurity; vast geographical areas to monitor; mixed population flows that include refugees, IDPs, pastoral and seasonal movements and economic migrants; massive population flows that overwhelm monitoring capacity; disinclination of individuals to provide information when there is no assistance being offered; pressures from communities to inflate figures to maximize future assistance; and political pressures to suppress accurate reporting on IDP movements. Additionally, due to the fluid nature of displacement in many contexts and the likelihood of recurring displacements, it is not possible to use movement data to provide estimates of population stocks.

# **_Population censuses_**

National population and housing censuses often provide the most comprehensive source of population data and offer the potential for estimating numbers of forcibly displaced people. To estimate the size of displaced populations a census would need to include questions on country (and/or place) or birth, year of (internal) 70 Other data collection methods may be used such as movement tracking systems, registration, big data etc.