Since the 1950 round of censuses, Statistics Division of FAO has published International Comparison Studies at the end of each round except for the 1980 round. For the1950 round the following subjects were covered in detail, including graphic presentation: Number and area of holdings, land tenure and land use; all classified by size of holding. For the 1960 and 1970 rounds detailed final reports were prepared covering all items proposed by the respective FAO Programmes. For the 1990 round a report covering selected items, considered important, was prepared. (see the Report and the Supplement.
Some further studies on the 1990 round of censuses are included in this report. Subject of these studies can be seen from the list of seven tables shown in the contents. In selecting these studies an attempt was made to cover some of the issues not covered before. These are:
Interpolation of country data, for countries, which did not follow the proposed FAO classifications. This refers to the classification of holders by age groups (Table 6) and the classification of holdings by number of parcels (Table 7). Data on holders classified by age groups are not planned for collection in 2000 round of censuses, so in a way, this was a last opportunity to make this kind of analysis. The interpolation was done using the graph paper.
Observation of trends for selected items (Tables 2, 3 and 4). This refers to the central and structural characteristics of holdings, and data on land tenure and cattle. The trends observed in these studies refer to countries for which the 1990 census round data were available and, in addition, the 1980 and/or 1970 round data were also available.
Presentation of data not analysed before. This refers to the classification of holders by sex (Table 5). Similarly, central and structural characteristics (Tables 1 and 2), which were calculated only once in the past for the 1970 round of censuses , were calculated this time for three census rounds.
Census rounds include all agricultural censuses conducted in a ten years period. Thus, the 1990 round include censuses conducted in the period 1986 – 1995. A few exceptions were made in order to increase the coverage. The following censuses were, therefore, included in the 1990 round: Brazil 85 (Tables 1 and 2), Bangladesh 96 (Table 5), and Chile 97 and Venezuela 97 (Table 7).
There are several problems in data comparability. The comparability between countries depends upon different concepts, definition and practices applied. The comparability of the successive censuses in the same country is generally better as each country tends to keep the same concepts, but there are cases when there are such changes in data, which cannot be explained with the information available in the FAO Statistics Division.
One of the problems with the comparability of successive censuses is in the fact that many countries do not take regularly the censuses, and even those that take them regularly, do not provide always comparable data. Number of countries in tables showing successive data is, therefore, relatively small (Table 2: 48 countries; Table 3: 19 countries; Table 4: 40 countries).
The main source of data for present studies are tables from the ‘Supplement to the Report on the 1990 World Census of Agriculture - International comparison and primary results by country (1986 – 1995)’ , ‘1970 World Census of Agriculture, Analysis and International Comparison of Results’  and unpublished International Comparison Tables: 1980 World Census of Agriculture, available in FAO Statistics Division . At times, also individual country results were used.
The subjects selected for this studies are, so called ‘structural items’, which are not expected to change considerably in time. Nevertheless, in the 20-years period under observation some major change can be noted in many countries, concerning the number and area of holdings, and number of head of cattle in holdings raising cattle, in particular.