1. Overview of census modalities
Technical review meeting on WCA 2020
Volume 2 – Operational guidelines on implementing census of agriculture Rome, Italy
30-31 January 2017
Chapters 8-11:
Overview of census modalities
Item 3
Jairo Castano
Leader, Agricultural Census and Survey Team
FAO Statistics Division

2. Contents
Background
Overview of census modalities: description, implementation steps, advantages and limitations:
Classical approach
Modular approach
Integrated census/survey modality
Use of registers as a source of census data
Country examples

3. Background
The WCA 2020 broadened the approaches introduced in WCA 2010, acknowledging that the census of agriculture can be conducted in different ways, using four main modalities:
Classical approach
Modular approach
Integrated census and survey modality
Use of registers as a source of census data
Main aim is to help countries to implement a census in the most efficient way, taking into account countries’ particular conditions.

4. Overview of census modalities
The classical approach: a census conducted in a single one-off operation (usually by complete enumeration) comprising the universe of agricultural holdings.
Modular approach: comprises: a) a core module undertaken by complete enumeration including all relevant frame items and eventually other items; and b) supplementary modules conducted using sample enumeration.
The integrated census and survey modality: integrates a multi-year programme of censuses and surveys. One option is AGRIS, a modular survey programme which has to be articulated with the agricultural census programme and conducted on an annual basis between two censuses.
Use of registers as a source of census data: registers and other administrative sources are used as a source of census data in combination with field data collection.

5. Comparison of census modalities
Classical
Modular
Integrated census/survey
Use of registers
Enumeration phases
One-off field operation
Multiple phases:
core module
supplementary module(s)
census core module
rotating thematic modules
One or more field operations and use of admin sources
Coverage of items
All census items collected in one-off operation
Core module includes items required at the lowest geo/admin level, and those to establish frames for supplementary module(s)
Census core module includes items required at the lowest geographic/admin level, and those to establish frames for rotating thematic module(s)
 Census items are collected through field operation and use of administrative sources.
Enumeration method
Complete enumeration exclusively or combined with sample enumeration
Complete enumeration for core module and sampling for supplementary modules(s)
Complete enumeration for census core module and sampling
for rotating thematic modules

6. Alternative census modalities
The classical approach is the most extensively used census modality. However, more and more countries would use alternative census modalities in the near future.
There are important reasons for using other census modalities:
budget limitation for census;
need to produce more frequent and timely agricultural statistics;
fast growing digital and mobile technology;
increasing availability and access to data from administrative sources and technical capacities to handle such data;
reluctance of some population groups to participate in the census and need to reduce respondent burden.

7. Some common issues for any census modality
Identify data content of the census:
The minimum requirement for a census, is to include all essential items, in order to enable national/international comparison and frame items for census modules or/and follow up surveys.
The final list of census items should be established in consultation with main stakeholders depending on country’s requirements, availability of reliable administrative and other data sources, financial and other resources.
In countries with well-developed registers, the use of administrative data sources (ADS) to cover census data items should be considered.

8. Some common issues for any census modality (cont’d.)
The frame for the census must be carefully established to ensure that all holdings are covered with no omissions or duplications.
Use of sample enumeration
efficiency considerations (precision versus costs);
desired level of aggregation for census data;
use of the census as a frame for ongoing sample surveys;
data content of the census;
capacity to deal with sampling methods and subsequent statistical analysis based on samples.

9. Some common issues for any census modality (cont’d.)
Use of thresholds
In many countries, a minimum size limit is adopted for holdings included in the census.
The rationale for this could be:
in the country there is a large number of very small holdings which make a marginal contribution to total agricultural production; and
their inclusion in the census greatly increases the workload and census budget.

10. 1. The classical approach
It is conducted as a single one-off operation in which all the census information is recorded. It also includes the short-long questionnaire concept.
All items collected at the lowest geo/admin level.
Can be conducted by complete enumeration, sample enumeration, or by a combination of both.
It is appropriate, for instance, when countries have an integrated census/survey programme or wishing to collect census items at the lowest geo/admin level.

11. 1. The classical approach: types of questionnaires
Single questionnaire: administered to all agricultural holdings covered by the census without regard of their type. It is easy to apply in the field.
Short-long questionnaire: The short questionnaire is administered to all holdings on a complete enumeration basis (to collect basic info), while the long questionnaire is administered only to:
holdings identified according to certain criteria (to collect more detailed info), such as being above an established threshold or belonging to a particular segment of the population;
a sample of holdings.
Other types of questionnaires - specific census questionnaires:
to fit different segments of the target population (such as household and non- household based holdings); or
for different provinces when these differ considerably in cropping and livestock systems, and in agricultural practices.
The use of Computer Assisted Personal Interview (CAPI) (see Section 4.2.1) can facilitate the field work. The devices can be programmed to use information collected in the short questionnaires to identify the sub-population to apply the long questionnaires. For example, the device can be programmed in such a way that the long questionnaire pops-up when a holding meets the threshold requirements or criteria related to the subpopulation of interest.

12. 1. Classical approach: advantages
Snapshot of the entire target population at a specified period. Comprehensive data sets at the lowest admin/geo level.
Data can be produced at lowest admin/geo levels with no sampling error. Tabulations can be done in line with high user’s requirements, including data for small administrative units and information on rare events, such as emerging crops, rare crops and types of livestock.*
Complete enumeration is much less demanding in respect of the characteristics contained in the frame than the sample-based census.
A good basis for building up a statistical farm register and an exhaustive sampling frame for subsequent regular agricultural surveys.*
* When census is conducted by complete enumeration *

13. 1. Classical approach: limitations*
Cost and administrative complexity.
It implies a high burden on respondents.
Risk to overburden the census questionnaire because of the high pressure from some policy makers or other stakeholders to include detailed items to collect data at the lowest administrative level.
Logistics: very large number of enumerators and supervisors required.
The amount of data to be processed is larger.
* Mainly when census is conducted by complete enumeration

14. 2. Modular census
Has a clearly distinguishable core module (on a complete enumeration basis) and one or more supplementary modules (on a sample basis).
An essential condition: data from the core module used as frame for the supplementary module(s). The census using the short-long questionnaire in one operation is not considered as modular census (no frame use).
A ‘module’ is defined as a group of data items to be collected on a specific target population (e.g. holdings with livestock).
All essential items should be covered by the core and supplementary module(s).

15. 2. Modular census (cont’d.)
Core module (CM) must include the items required at the lowest geographic or administrative levels, and/or needed to establish sampling frames for the supplementary module(s).
CM should include all frame items. It should also cover rare events (unusual crops or livestock), which would not be possible to estimate from SM(s) because of high sampling errors.
SM(s) use the frame generated by the core module to target specific populations and should include the rest of the agreed census items that are not included in the core module.
Countries should make this decision depending on their national requirements, taking into account cost and resource availability, including financial and human resources.

16. 2. Modular census modality: ways and steps for implementation
Two ways of implementing the modular approach:
implementing core and supplementary modules separately (common way)
implementing the core module and the supplementary module(s) as part of a single data collection operation (difficult in practice).
Sources of frame data for supplementary modules:
The census core module;
An agricultural module/section of the population census;
Administrative registers.

17. 2. Modular census: advantages
The combination of core’s and SM’s items allows the modular census to produce a wider and country-specific range of data, for which small area estimates are not so important.
More effective use of available budget to collect country relevant information.
Allows a focused and more detailed training of field personnel.
Countries with a not well established system of agricultural surveys and limited budget may find the modular approach as a logical first step towards the creation of a system of integrated agricultural censuses and surveys.

18. 2. Modular census: limitations
Risk of having a CM with too many items (due to pressure from stakeholders).
The availability of well trained professional staff in sampling could be a challenge.
There are limitations in terms of cross-tabulation between variables in the core and in the supplementary modules (SMs) or between variables in different SMs not conducted jointly.
If the time lag between the implementation of the CM and SMs is too long, the benefit of having a good frame from the CM disappears. A frame update would be needed adding to the cost.
If SMs are undertaken at the same time as the CM there exists the risk of loss of data quality if not properly organized.
It could be difficult to mobilize additional funds for SMs.
In the absence of good planning, the conducting of the CM and publication of results can jeopardize a better preparation of SMs.

19. 3. Integrated Census/survey modality
This new modality features a census core module (to be conducted on a complete enumeration basis) and a number of several rotating thematic modules (to be conducted annually or periodically on sample basis over a 10-year period).
An example of a survey programme with rotating thematic modules is the new Agricultural Integrated Survey programme (AGRIS).
All essential items should be covered by the census core and rotating thematic modules.
The census core module should mainly provide frame data needed to implement rotating thematic modules.

20. 3. What is AGRIS?
The AGRIS is a modular survey program which is to be articulated with the agricultural census programme and conducted on an annual basis between two censuses.
It consists of one annual core module (crop and livestock production) and four rotating modules: ‘economy’, ‘labour force’, ‘machinery and equipment’, and ‘production methods and environment’. Additional modules can be added as needed.
In the integrated census and survey modality, AGRIS core and rotating modules are synchronized with the agricultural census core module and operate over a 10- year cycle.

21. 3. Integrated census/survey: recommended modules flow
 Years 1 2 3 4 5 6 7 8 9 10
Agricultural Census core module (•) and inter-census survey (o) • o 
AGRIS Core Module
Holding roster (ID & socio-demo)
Crop/livestock production
Key thematic issues
Rot. Module 1
Economy
Rot. Module 2
Labour
Rot. Module 3
Machinary, Equiment, Assets and Decisions  •
Rot. Module 4
Production Methods and Environment • 

22. 3. Integrated census/survey modality: advantages
Effective use of available budget to collect country relevant information on an annual basis.
More detailed information available on topics of interest.
Focused training of field staff.
Wider set of census items.
Allows the establishment of a system of integrated agricultural censuses and surveys.
In addition to those advantages, for countries that do not have a functioning agricultural statistics system, this modality being a 10-year integrated census/survey programme, lays the foundations for the creation of such a system to produce a regular flow of basic data. It will allow the generation of 65% of the Minimum set of core data recommended by the Global Strategy and will also provide basic data for monitoring the relevant Sustainable Development Goals (SDGs). Finally, AGRIS is expected to generate the flow of quality data required to monitor regional policy frameworks, such as the African Union Comprehensive Africa Agriculture Development Programme (CAADP).
Some countries may have 5-year census programme instead of 10-year programme. In this case, the implementation of AGRIS should be adapted to this particular situation with possibly more frequent implementation of the rotating thematic modules.
See

23. 3. Integrated census/survey modality: limitations
The risk of expanding too much the census core module resulting in high cost which will reduce the relative benefits of this modality.
Conducting the census core module and AGRIS core at the same time (when relevant) requires good survey planning and sampling capacity.
The limitations in terms of cross-tabulation between variables in the core and in the rotating thematic modules or between variables in different rotating thematic modules not conducted jointly.
Difference in the reference period for different census items collected in the census core and the items in the rotating thematic modules.

24. 4. Use of registers as a source of census data
A meaningful part of the census items for the entire population of the CA (or for part of it) comes from existing admin sources created for non-statistical purposes.
The data could come from one or several administrative sources. Usually these are used in combination with field data collection.
Thus the definition of the population of interest and the data collection protocols commonly is out of the control of the census agency.
As the objects already exist in the data source, a selection need to be made of objects (holders or holdings) and variables that are relevant to the census.
The cases where only the identification items are taken from administrative sources (such as name, address and location of the holding) are not considered as part of combined census modality, in these cases data from administrative sources can be used for construction of the census frame.

25. 4. Use of registers:Quality considerations
Some information in administrative sources could be of low importance for administrative purposes which may result in lower statistical quality.
The purpose and method used to collect data should also be taken into account to detect possible systematic errors or systematic bias in the register.
The following quality aspects need to be carefully considered:
Relevance (content) of the administrative data sources.
Accuracy: an admin source is of good quality if a large proportion of the variables required for the census exists in the register and data are reliable.
Data coverage: one important accuracy category: under-coverage or over-coverage of units, and misclassification of items.
Unreported events: data related to the reference period are not available in the source referring to an event from which parameters are to be derived: e.g. births, deaths or loss, sales, etc. of livestock.
The information from administrative sources has to be coherent and comparable with data from other sources and over time.
The timeliness dimension (difference between the reference period and the availability of the results) when using administrative data source.
Accessibility in terms of physical access to the information in the admin source.
Possible problems are: missing data when some or all characteristics for a given unit are missing; errors in the variables when erroneous values for certain variables are registered (e.g., when the respondents give erroneous identification numbers for administrative data sources in the questionnaire).

26. 4. Use of registers: Ways of using
The starting point (like in all census modalities) is to define the data content of the census in terms of data items to be covered.
Next step is to decide on the way to use the admin source. Possible ways or approaches are:
Split data approach: admin sources are used to provide some of the variables for all of the holdings.
Split population approach: Data from admin sources are used for some holdings where these data are of sufficient quality, and other statistical sources are used for the remainder of the holdings.
Combining the two approaches: administrative sources replace the field data collection for some of the variables for part of the holdings.
Pre-filling answers in the questionnaires which are to be checked by respondents during the census.
Totally replacing the census data collection, on all census characteristics and for all units in the census with data coming from one or more admin sources (no common).
Pre-filled questionnaires have three main benefits:
They help reduce the burden on data suppliers by saving them time (assuming that checking and correcting is quicker than finding and entering data)
They allow to check the quality of the administrative data
They are very flexible, particularly where the coverage of administrative data is not as complete as would be required for the other ways of use discussed above. They allow an easy data revisions/changes and adding additional information. The main disadvantage is the risk of bias introduced because some respondents may simply accept the pre-filled data without checking them, or may choose not to spend time correcting errors.

27. 4. Use of registers: Implementation
Assess the usability of the source/register and quality (see before);
Assess legal basis (to access and use); consultations with owners (concepts, definitions, classifications used, reference period, coverage); public support (to statistical use).
Design a government-wide project to outline responsibilities and the necessary work:
Make an inventory of sources, usability/quality.
Develop the content for the census.
Decide items to be produced from what kind of data sources.
Determine steps to link datasets.
Develop communication strategy for the use of registers.
Plan the budget for the particular preparatory work related to the use of registers for the AC.

28. 4. Use of registers: Advantages
Reduction of cost of census data production.
Reduction of the burden on respondents.
By combining the data collected in the field with the data from administrative sources, new derived variables can be created.
It allows compilation and publication more frequently and faster.
Non-response rate can be either significantly reduced or eliminated (when data on the entire target census population are included in the administrative sources).
It could significantly improve the quality of the source and leads to a substantial harmonization of certain information between different institutions.
As a result of more efficient and faster operation the public perception of statistics may become more favourable.

29. 4. Use of registers: limitations
Linkage of datasets are difficult/impossible if legal background is inadequate.
It could be very difficult to establish a good cooperation with register owners.
The cost for the access to the admin data could be too high.
When there is different population coverage, admin sources can be used for pre-filling the questionnaires only on common population while other units need to be enumerated.
Incoherence of concepts, definitions, classification and reference periods could hamper the use of admin sources.
Problems related to linking data from various data sources.
Problems on quality or stability may arise due to political changes.
Timeliness and punctuality.
If an admin source is abolished, it is difficult to provide comparable statistical data series.
Substantive or technical changes in the admin sources may not be detected immediately.
Comparability over time is strongly influenced by the change in the level of coverage in the different years and can give misleading results.

30. Discussion points Clarity in the discussion of modalities.
How can the chapters be improved to facilitate census planners’ decision about what modality to use?
Relevance of country examples.

31. MANY THANKS