Many nations do not collect foreign resident information in their censuses or surveys; and those that do often lack this data by age, sex, and race. We can surely say that the absence of this information is one of the major obstacles in estimating U.S. emigration abroad by the above method.
The data-sources. - In my search to find as many foreign census publications as possible with the necessary data, I used four major information-sources: (1) the Bureau's main library; (2) the Bureau's Center for Information Research (CIR) library, (3) the United Nation's statistical library in New York, and (4) the library of the Population Research Center (PRC) at the University of Texas, at Austin. Generally, only the CIR and PRC libraries contained useful information for the above study.
The CIR data-base included demographic and social data for 202 countries displayed in 92 individual tables. Only one of the tables in the data-base, table (number 40), however, was useful. It was entitled: "Population by Nationality and Sex, and Urban/Rural Residence"; this table presented data on foreign residents by citizenship and sex, but not by age.
Ultimately, I picked 87 countries with foreign-resident nationality information; but only 43 had data on U.S. residents (i.e. emigrants) and merely 15 of them the required age/sex information needed to apply the cohort survival method. Furthermore, some of the data were grossly outdated.
A major difficulty was that many countries had collected foreign born resident data by citizenship, but not by birth; and my purpose was to estimate U.S. born emigrants not just U.S. citizen emigrants (which also include foreign born persons). In general, the CIR data-base was not very useful to me.
By contrast, the PRC library at Austin, Texas, was very useful as a source of foreign census information. The library included a vast collection of foreign census and survey publications and I spent about 2 days there searching and checking publications for data on U.S. residents in foreign countries. Although I found much useful data, usable material was still sparse. For instance, I found once again that many countries had no foreign resident information whatsoever; others had only one census with the required information (I needed two for the survival method); and still other countries had two censuses, but not exactly 10 years apart. In addition, I had to adjust several age distributions which were not in the standard 5 or 10 year age-groupings. In many instances, other non-standard displays of the census information required manipulations and adjustments of the available data.
Age data. - In particular, for age distributions not in standard form, I constructed a LOTUS spreadsheet called AGSX that arranged the age-data in standard 5-year age group format. And for countries just showing U.S. foreign-resident counts but no age breakdown in their latest two censuses, I used the proportional age distribution of U.S. residents in Canada. Although we may question whether Canada has, or has not, a "typical" U.S. born emigrant age-distribution (compared to other countries), Canada was the only country with very reliable U.S. resident age data conveniently presented in standard 5-year age groups. Originally I tested the adequacy of the Canadian age-sex U.S. resident distribution to serve as a standard by comparing with the age-sex distributions of Mexico, (which has the largest number of U.S. emigrants abroad) and of Australia. Results showed that the Canadian age-sex distribution pattern was closely equivalent not only to the average age pattern of U.S. residents in Australia and Mexico but also to that in many other countries with published census data on U.S. residents.
Age Extension and Race Allocation
For countries with data on U.S. residents by age and sex, the age distributions of these persons usually did not go beyond 65 years old and over, the open-ended age interval at the initial census date (i.e. 10-years older at the terminal census date) had to be set at 55 years old and over. These age levels were used both for the countries with published foreign born resident-data and for the countries in which I had to create the required data from the State Dept. U.S. registrant assumptions. Since our national estimation and projection programs require all population estimates to reach age 85 years and over, I extended my emigration estimates to that age group by assuming the same proportional breakdown between 65 yrs. and over to 85 yrs. and over taken from the age distribution of our current estimate of total annual emigration (i.e. 160,000 persons).
For the Race breakdown of U.S. born residents abroad, I adopted the same race subdivision used in our current annual estimate of total emigration. (Tables 1 and 1A).
Estimates by age and sex for individual countries in the study are shown in Table 2.
Table 3 shows emigration estimates by sex for all countries in the study, data-sources used, type of nationality reported, and type of age-sex distribution used for the estimated U.S. emigrants.
Table 4 shows estimates of U.S. born emigrants derived from the State Department assumptions, by sex (with sex ratio used to estimate sex), and age distribution used.
Tables 5 and 6 show steps used in the application of the cohort survival method, by sex, as applied to Australia. This layout was used to derive the emigration estimates for each individual country in the study.
Life Table Selection
The cohort survival method requires, in part, the selection of a suitable mortality level to survive U.S. residents abroad from census-to-census, and I reviewed several possible representative life tables. Eventually, I chose the 1979-81 U.S. Life Table to represent U.S. emigrant-mortality for most of the countries selected. For other country-groups I used the Coale-Demeny West # 23 Life Table; and for still other countries, those whose latest censuses were in 1970 or earlier, I used the 1965 U.S. Life Table (see Tables 7,8, and 9).
DERIVATION OF ESTIMATES
Following the age and sex adjustments and life table selections for U.S. residents in the countries with available census data on these persons, I applied the cohort survival method via two separate spreadsheet arrangements, one for each of the sexes. In a single interconnected operation these spreadsheets did the following: (1) survived the initial emigrant population by age according to the indicated age-specific mortality selected; (2) reverse-survived the population estimated in the preceeding step; (3) averaged the two resulting distributions to generate a final survived population by age; and (4) calculated the differences by age group and sex between the survived population at the terminal census date and the corresponding census counts. These differences represented the estimates of net emigration of U.S. residents during the particular country's intercensal period. Results showed total net annual U.S. emigration by age and sex, centered around 1980, for countries whose last two census had U.S. born resident data. These countries were: Australia; Brazil; Canada; France; Great Britain; Ireland; Mexico; New Zealand; Sweden; Switzerland; and Venezuela.
For countries without census data on foreign residents, I used State Department information on U.S. citizens registering at U.S. Embassies and Consulates abroad to estimate total U.S. native-born persons in the indicated countries. Subsequently, I used model age-sex distributions derived from the above countries with census data (grouped according to cultural "similarity") to represent U.S. resident age-sex distributions for the countries without census data on foreign emigrants. Hence, I was able to apply the cohort survival method to the second group of countries in the same way as I had for the countries with census data on U.S. residents.
Some additional comments. - Within the methodological framework developed for this study, we note that many other alternative estimates could have been derived by: (1) selecting alternative mortality patterns; (2) chosing different age distribution patterns; (3) making different assumptions regarding the proportions of U.S. registrants abroad, and (4) assuming different proportions of U.S. registrants abroad. However, the derived native-born emigration estimates by age, sex, and race are not implausible. For example, the countries selected in the study probably reflect those which are major magnets for U.S. emigrants and are also likely to include those which host most of U.S. emigration. And although the age/sex distribution chosen as prototypic for most U.S. emigrants abroad are not unreasonable, the quoted State Department proportions on the composition of U.S. registrants abroad have to be taken at "face value". But, even with some variations in the above assumptions, the "true" estimates will probably fall within a short range encompasing the estimates shown in the table. In particular, the race composition pattern of the U.S. born emigrant estimates was assumed the same as that used by the Census Bureau's estimates and projections staff in developing their current estimate of total annual U.S. emigration abroad.
We should note that, for some countries, the estimated emigrant age-sex groups show negative emigration; this probably means that at certain ages there is an outflow of U.S. born emigrants from the specified country. This is not inconsistent with reality and expected given the methodology (i.e. cohort survival) used to generate the estimates.