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IPS153 John D.
complete (and free of erroneous records) estimating stocks and flows
becomes simply a matter of counting records contained in the SPD in two
time periods (timepoints), including those records that are common to the
two time periods (timepoints). In the journey to achieving these goals, the
methods developed can provide coherent estimates and when the goal is
achieved can be provide reassurance around that achievement. As the
coverage of the SPDs improve so too does the quality of the estimates of
stocks and flows.
In summary, key characteristics of the proposed methodology to
estimate gross population flows include:
Only one additional assumption is required beyond those required for
estimating the population size, that the SPD is considered representative of
the population.
Violation of this assumption may only have a low impact, as → , the

impact any violation goes to 0. In practice the size of the SPD is going to be
close to that of the population (> 90%)..
A coherent set of estimates for stocks and flows through reusing the
same data sources and using the stock estimates as a basis for estimating
flows.
In terms of simplicity, the same data sources are used for estimating stocks
as well as flows in a coherent system using simple DSE methods. Combining
simple DSE methods with appropriate set intersection diagrams will aid
explanation of these methods to users.
Further work in the PECADO project includes investigation of methods to
detailed disaggregate state estimates by geography. If this is achievable, it
may also be feasible to further extend the methods to estimate internal
migration flows.
The author notes, the modernisation of systems of population estimates
requires new and innovative methods and applications to fully exploit
administrative (and other) data sources. There is a lot to be gained by the
international statistical community in sharing ideas and practices and hope
that this paper can make a contribution in this regard.

References
1. EUROSTAT (2003). Demographic statistics: Definitions and methods of
collection in 31 European Countries. European Communities.
2. EUROSTAT (2015). Demographic Statistics: A review of definitions and
methods of collection in 44 European countries. Eurostat.
3. Lanzieri, G. (2013). On a New Population Definition for Statistical
Purposes Note. In CES Group of Experts on Population and Housing
Censuses. UNECE.

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