Project Within the
the national GIS project - which was designed to supply a geographic base for
management of population statistics - within the planning and implementation of a
national population census. This will be accomplished by presenting the principal
strategies that were used by us in integrating these two projects, as well as a
description of the key phases.
the utilization of census resources to solve the problems inherent in setting up the
GIS, while at the same time, it enabled the census to take advantage of GIS
technologies to solve census problems. The integration allowed for significant
improvement of field work during the census, as it relates to covering buildings,
which improved population coverage, which is and always has been, the main
objective of the census.
of the GIS project was absorbed within the cost of the census budget, without
requiring an increase in funding.
earlier the project of setting up the GIS is commenced during the course of
preparations for the census, the earlier that benefits can be reaped from the
unique by-products the GIS has to offer.
the projects and which are likely to be solved, or at least to be reduced, as a
result of integration.
the GIS, and the main phases of the project are described, taking into account the
schedule that was imposed and the costs involved also compared with the costs of
using alternative methods. There is an emphasis on the main advantage of
integration in terms of the GIS: the creation of a national mapping infrastructure at
the level of buildings and streets, together with a national addresses file.
phases of the census, and the advantages of the integration from the perspective
of the census project.
integration of the two projects, and several challenges for the future are
Geographical Information System as the infrastructure for management of population
statistics at the national level, or even the local level, would not be surprised to
learn that one of the main problems, which is a bothersome bottle-neck, is the
problem of entering the basic geographical data infrastructure in the computerized
system or, in other words, the digitization of the maps at the level of buildings and
roads. Anyone who has attempted to apply the wonders of technological development
related to geographical information systems has quickly found out that without
massive input of basic geographical data, these wonders are unattainable.
symbols of streets and house numbers with buildings on a digital map. In most
cases, any statistical data that may be collected does not allow for geographical
identification at the coordinate level. Detailed population data may include, under the
best cases, geographical identification of the address. That is also the case
regarding data which come from such sources as property tax files, electric
company and telephone company records, etc. But once the address data is located
in a computerized system (GIS) and each building "knows" its address (or its
addresses, in the many cases when a building has more than one possible address),
any piece of external information with a defined geographical dimension can be
added to the system by linking it to the address.
certainly on the critical path of the GIS system set up and are threshold problems
that need the main resources of the set-up project.
national population census, is the problem of complete mapping of all residential
buildings in the country. Identification of all buildings which may be inhabited by
people is one of the most important and most difficult tasks during the preparation
and implementation phases of the census, regardless of the actual census method
employed. If the census method is based on the drop-off and pick-up of
questionnaires by enumerators, the problem of covering the buildings is compounded
by the problem of distributing homogeneous work loads for the enumerators.
estimate the anticipated results of the census by estimating the expected number of
households in each area at a relatively high level of geographical detail, so that the
enumerator's work load will be manageable (In the Israeli last census, an enumerator
could accomplish the enumeration of 275 75 households during the period of time
allocated for that). In the past, as in many other countries, before the population
census began in Israel, "a census of buildings" was conducted which served, inter
alia, to update the maps to be given to the enumerators working on the population
census. This update included not only a correction of the number of buildings
according to findings in the field, but also a listing of the addresses which helped
enumerators to orient themselves in the field during their work. This action was
very expensive because it required a great deal of particularly skilled staff and
because it lasted for a relatively long period of time.
projects, the census planners faced the question of how to come up with a combined
solution which would serve both of the projects equally well.
Integrating the GIS in the Census
census project. In essence, setting up the GIS can only be a relatively small part,
from all perspectives, of the planning and implementation process of the population
census. Therefore, if the subject is integration, the intention is to integrate the
setting up of the GIS project within the census project, and not the other way
around. This is not intended to belittle the size and the importance of the GIS tasks,
but these are dwarfed in comparison with the overall census tasks.
the lead project, while setting up the GIS would be a by-product to make the mapping
procedures for the census more efficient. This strategic decision guided those
planning and implementing the project throughout the course of their work, and
enabled them to make quick decisions in the event of a conflict of interest between
the two projects.
census (which is almost synonymous with the GIS, thereby emphasizing the principle
for the purpose of mapping; and
maximum standardization of the work processes and the results (the maps).
need to be reduced because "any excess weight could cause the entire project to
sink." Any attempt to put more items on the maps, or to require detailed levels of
engineering accuracy, was rejected out of hand in order to reduce the project to
reasonable dimensions which would allow its implementation.
about 600,000 buildings out of a total of 700,000 buildings, a complete mapping
project of all localities is no simple task.
implementation of the census processes involved a number of key stages:
in Israel and around the world, formulation of a conception and determination of
phases of work, along with a series of experiments. The experiments were divided
of the existing inventory of maps of all types, in all the relevant media (digital,
paper, aerial photographs).
this stage included planning and drafting of implementation requirements, in close
cooperation with the Survey of Israel.
cases where digitized maps already existed, these were used if they could be made
to meet the requirements. Similarly, paper maps were also digitized.
would include streets and buildings, but no text, only a limited number of
characterizations (categories of streets and roads, type of building, etc.). An
important step was planning and implementing the procedures for receiving, checking
and entering the digital maps into the CBS computers.
Population Register. For the purpose of adding addresses to maps, a special
application was developed which made use of the addresses file within the Population
Register. This application, pioneering in its time, reduced the amount of errors
during the process, which was called "address ascription - application." During this
being printed out.
developed which utilized the problematic and not always up-to-date information from
the National Population Register concerning the size of the population in the polling
district and by address. Additional data included population estimates in statistical
areas (holding an average of about 1,200 households) which underwent automatic
corrections (standardization). The redistricting was performed in a computer-
assisted procedure. In order to divide a locality area into EAs, the area divider
received information regarding the standardized population in each polling district
within a given statistical area (polling districts are included in their entirety within
statistical areas). Division into polling districts was used as a system default; in
other words, a polling district was defined as an EA if it met the criteria of
population size. This application enabled arranging polling districts to the desired
size of about 275 households in each EA, creating additional EAs and the uniting
of existing areas, by changing the borders of the polling district. This method was
used for most of the EAs, except in those cases where prior information indicated
that the data from the Population Register was very out of date. In such cases,
division was done using the same system, but without relying on the Register data.
EAs enumerated during the census, in only about 130 cases (some 2%) were
particularly large EAs discovered, forcing field workers to split them up. Also, the
number of small EAs was less when compared to the previous census.
automated. Furthermore, the system supplied maps for the higher echelons: section
maps for supervisors, and locality maps and other types of maps for the more
senior management echelons. The maps, which were totally consistent with each
other (complete matching of borders), were of a much higher quality than those we
were familiar with from previous census.
work, in order to improve coverage of the buildings. The files were integrated into
the computerized field work system, so that each supervisor could question the
enumerators under his responsibility in cases where there was a lack of
information on any building found on the EA map.
which was performed during the questionnaire data entry process utilizing the
census data optical data entry system. The addresses files are what supported the
automatic coding system, during which time the addresses reported on the
questionnaire were linked with GIS addresses file. Cases where links were not
made were identified and sent for coding by the geographic experts using a
collected by the enumerators during the census enumeration had been stored. This
data included addresses that were not in our possession at the time the maps were
prepared, as well as many corrections and revisions, which enabled updating of the
maps as of the day of the census. This activity is now underway.
questionnaires with the addresses in the GIS, in order to provide coordinates and
GIS-type addresses for each household and individual in the census population
according to the building coordinates found on the GIS maps. Also during this
stage, the final linkage between the building records within the GIS and the data
from the questionnaires is performed. The result of this linkage is that each
respondent is linked to coordinates and through them, to all the geographical
information which is included, or will ever be included, in the database of the
census GIS. At the same time, each building in the GIS is linked to a population
along with its census characteristics. This stage will begin as soon as the
questionnaires file will be ready.
place in November 1995), maps were produced for the large localities. Today, the
process of producing other cartographic products is in progress and many maps,
which will join the various publications of the census, are currently being prepared.
completed, and will enter full gear in 1998.
Below is a schedule of the principal phases of the work. Naturally, with different
allocations of resources, some of the stages could have taken more or less time.
However, there is an internal dependence between the activities. For example, a
delay in the census by one year made it necessary to repeat the update on the
original maps, which required allocation of special resources.
this was that people did not have prior experience in many of the necessary
activities, particularly considering the scope of such a large undertaking (not even
in the private professional sector).
as to make them meaningful in international comparison. We can say, however, that
the cost of setting up the GIS did not exceed the costs of the alternatives that would
have been required to map the residential areas prior to the census. In total, the
cost of setting up the GIS was absorbed within the census budget, without requiring
any special additional funding.
the GIS Project
was integrated within the census project from the initial planning stages of the
census (inclusive). This integration enabled the planners and implementers to gain
the maximum benefit from the investment in setting up the GIS. Actually, there wasn't
a single census phase that did not benefit from the GIS integration. I will point out
the main advantages:
precisely the same manner for each of the EAs, is an advantage which was possible
following production of maps from the GIS. Furthermore, the fact that the planners
could determine with certainty the contents of the maps and know that each
enumerator had in his possession exactly the same type of map, made the planning
easier. It is difficult to estimate the contribution of this type of standardization.
But after a peek at the maps used in previous census polls, which were a function
of the various types of sources used to prepare them, it can safely be argued
that in previous censuses, the quality of the maps used in some cases did not allow
the enumerator to fulfill his role as planned. This situation was prevented from
occurring in the 1995 census thanks to the contribution of the GIS.
field level was another contribution of the GIS system. In comparison with previous
census polls, the new method described above enabled a significant savings in the
size of the infra structure which served the census field setting. Furthermore, the
very fact that almost all the enumerators were allocated reasonable work packets,
not too big and not too small, contributed to improving the work process, and in the
final analysis, did much towards improving the quality of the results.
enumerators' maps and the addresses file located in the computers in the sub-
regional offices enabled efficient supervision of the enumerators' work, primarily
as it relates to covering buildings. An enumerator was required, through the use of
computer reports, to supply the supervisor with an explanation concerning each
building found on the map, either using the questionnaires from the respondents, if
the building is for residential use, or by some other reasonable explanation
concerning other uses of the building. This process not only enabled monitoring of
the enumerator's work, but also made an important contribution towards freeing the
supervisors for additional duties, which enabled additional improvement in the quality
of the data collected.
work and places of residence from five years ago that were reported in the
a result of the census, exceed what we have known to date, both in terms of their
quality and their variety. Without examining all the advantages of producing census
products on the basis of the GIS, I would mention only the flexibility in defining the
new geographical units. In reality, the moment the data from the questionnaires is
linked to the buildings in the GIS, we can retrieve data on new geographical units
from the resolution of a digital map (from the building level and beyond). In
practical terms, a client can request data on any geographical unit he defines (of
course, subject to the limits resulting from the need to protect the confidentiality of
improving the ability to cover the entire population and raising the quality of the
geographical data supplied by the census. It should be borne in mind that these two
items were the key objectives that were set during the planning stage for the 1995
Census of Population and Housing.
for the Future
statistics in the context of the census is, indeed, a large part of the contribution
which the project made to the organization, but is not the entire contribution. In
essence, without the need for additional investment, the CBS has become, with the
end of the census activities, the owners of a national GIS which can serve the
Bureau in the future.
fact that at the end of the census a computerized geographical system with the
characteristics described above was created, justifies the integration between the
GIS and the census project. But this is not the case. The contribution by the GIS
to the future management of official population statistics can not be exaggerated; its
contribution will not only be felt on population statistics, but that is beyond the scope
of this paper.
enable us to maintain good matching between the contents of the GIS and the situation
in the field at any given point in time. A second challenge is matching the GIS to the
needs of the other CBS units. We are only beginning to face these two challenges.
ever-growing population of data consumers. This challenge has already been
seriously considered in our plans for distributing the census data. From the
experience we accumulate, we hope to learn ways to market the non-census
geographical statistical data.
the one hand, we will have to develop tools which will enable geographical sampling
based on the GIS. It may be correct to say that in terms of the sampling approach
this is not an earth-shattering innovation, but without the ability to take population
samples from maps, the existing sampling methods work mainly on the basis of
various lists from which the samples are taken. Addition of the spatial component is
likely to lead to interesting developments. A second area is the integration of the
spatial component in statistical analysis. This does not mean displaying statistical
analysis on maps, but this relates to what is referred to as "geo-statistics": fully
incorporating the spatial component within the analysis. Preliminary steps have been
taken around the world in this field, and Israeli researchers have played an
important role in this. But there is still much work to be done, and we have only
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