DEFINITIONS AND EXPLANATIONS

Population coverage.--The data for 1969 (covering the period March 1968 to March 1969) shown in this report relate primarily to the population of the United States 1 year old and over. Approximately 1,028,000 members of the Armed Forces living off post or with their families on post are included, but all other members of the Armed Forces are excluded. The coverage of the population for the earlier survey years was essentially the same.

The

Farm-nonfarm residence.--The farm population refers to rural residents living on farms. method of determining farm-nonfarm residence in the present survey is the same as that used in the 1960 census and in the Current Population Surveys since 1960, but differs from that used in earlier surveys and censuses. According to the current definition, the farm population consists of all persons living in rural territory on places of less than 10 acres yielding agricultural products which sold for $250 or more in the previous year, or on places of 10 acres or more yielding agricultural products which sold for $50 or more in the previous year. Rural persons in institutions, motels, and tourist camps, and those living on rented places where no land is used for farming are not classified as farm population.

Metropolitan-nonmetropolitan residence. --The population residing in standard metropolitan statistical areas constitute the metropolitan population. Except in New England a standard metropolitan statistical area is a county or group of contiguous counties which contains at least one city of 50,000 inhabitants or more. In addition to the county, or counties, containing such a city or cities, contiguous counties are included in a standard metropolitan statistical area if according to certain criteria they are essentially metropolitan in character and socially and economically integrated with the central city. In New England, standard metropolitan statistical areas have been defined on a town rather than county basis. Standard metropolitan statistical areas of this report are identical with the standard metropolitan statistical areas of the 1960 census and do not include any subsequent additions or other changes.

Mobility status. --The population of the United States has been classified according to mobility status on the basis of a comparison between the place of residence of each individual at the survey date and the place of residence 1 year earlier. This comparison restricts the classification in terms of mobility status to the population 1 year

The information on mobility status was obtained from the responses to a series of inquiries. The first of these was "Was ... living in this house March 1 a year ago?" If the answer was "No," the enumerator asked, "Was ... living in this same county on March 1 a year ago?" If the response was "No" again, the enumerator asked, "What State (or foreign country) was... living in on March 1 a year ago?" In the classification three main categories are distinguished:

1. Nonmobile persons or nonmovers.--This group consists of persons who were living in the same house at the end of the period as at the beginning of the period.

2. Mobile persons or movers.--This group consists of all persons who were living in a different house in the United States at the end of the period than at the beginning of the period.

3. Persons abroad.--This group consists of persons, either citizens or aliens, whose place of residence was outside the United States at the beginning of the period, that is, in an outlying area under the jurisdiction of the United States or in a foreign country. These persons are distinguished from "movers" who are defined here as persons who moved from one place to another within the United States.

Mobile persons are subdivided in terms of type of mobility into the following two major groups:

1. Same county (intracounty).--Those persons living in a different house but in the same county at the beginning and end of the specified period.

different county (inter2. Migrants, or county movers).--This group consists of persons living in a different county in the United States at the beginning and end of the period.

Migrants are further classified by type of migration on the basis of a comparison of the State of residence at the end of the period with the State of residence at the beginning of the period.

1. Migrants within a State (intrastate migrants), excludes intracounty movers.

2. Migrants between States (interstate migrants). Age.--The age classification is based on the age of the person at his last birthday.

Median age.-- Median age is that which divides the population into two equal parts, one-half of the population being older than the median and one

Race.--The population is divided into three groups on the basis of race: white, Negro, and "other races." The last category includes Indians, Japanese, Chinese, and any other race except white and Negro. In most of the tables of this report, "other races" are shown in combination with the Negro population.

Years of school completed.--Data on years of school completed in this report were derived from the combination of answers to questions concerning the highest grade of school attended by the person and whether or not that grade was finished. The questions on educational attainment apply only to progress in "regular" schools. Such schools include graded public, private, and parochial elementary and high schools (both junior and senior high), colleges, universities, and professional schools, whether day schools or night schools. Thus, regular schooling is that which may advance a person toward an elementary school certificate or high school diploma, or a college, university, or professional school degree. Schooling in other than regular schools was counted only if the credits obtained were regarded as transferable to a school in the regular school system.

Marital status. --The marital status classification identifies four major categories: Single, married, widowed, and divorced. These terms refer to the marital status at the time of enumeration.

The category "married" is further divided into "married, spouse present," 'separated," and "other married, spouse absent." A person was classified as "married, spouse present" if the husband or wife was reported as a member of the household even though he or she may have been temporarily absent on business or on vacation, visiting, in a hospital, etc., at the time of the enumeration. Persons reported as separated included those with legal separations, those living apart with intentions of obtaining a divorce, and other persons permanently or temporarily estranged from their spouses because of marital discord. The group "other married, spouse absent" includes married persons employed and living for several months at a considerable distance from their homes, those whose spouses were absent in the Armed Forces, in-migrants whose spouses remained in other areas, husbands or wives of inmates of institutions, and all other married persons (except those reported as separated) whose places of residence were not the same as that of their spouses.

For the purpose of this report the group "other marital status" includes "widowed and divorced,"

Household.--A household includes all of the persons who occupy a house, an apartment, or other group of rooms, or a room which constitutes a housing unit under the 1960 census rules. A group of rooms or a single room is regarded as a housing unit only when it is occupied as separate living quarters, that is, when the occupants do not live and eat with any other persons in the structure, and when there is either (1) direct access from the outside or through a common hall, or (2) a kitchen or cooking equipment for the exclusive use of the occupants.

Household relationship

Head.--One person in each household is designated the "head." The head is usually the person regarded as the head by the members of the group. The number of heads, therefore, is equal to the number of households.

A relative of the head is any household member who is related to the head by blood, marriage, or adoption.

Primary families and individuals. --The term "primary family” refers to the head of a household and all other persons in the household related to the head by blood, marriage, or adoption. If nobody in the household is related to the head, then the head himself constitutes a "primary individual." A household can contain one and only one primary family or primary individual. The number of "primary" families and individuals is identical with the number of households.

Labor force and employment status. --The definitions of labor force and employment status in this report relate to the population 14 years old and over.

Employed.--Employed persons comprise (1) all civilians who, during the specified week, did any work at all as paid employees or in their own business or profession, or on their own farm, or who worked 15 hours or more as unpaid workers on a farm or in a business operated by a member of the family, and (2) all those who were not working but who had jobs or businesses from which they were temporarily absent because of illness, bad weather, vacation, or labormanagement dispute, or because they were taking time off for personal reasons, whether or not they were paid by their employers for time off, and whether or not they were seeking other jobs. Excluded from the employed group are persons whose only activity consisted of work around the house (such as own home housework, painting or repairing own home, etc.) or volunteer work for

Unemployed.--Unemployed persons are those civilians who, during the survey week, had no employment but were available for work and (1) had engaged in any specific jobseeking activity within the past 4 weeks, such as registering at a public or private employment office, meeting with prospective employers, checking with friends or relatives, placing or answering advertisements, writing letters of application, or being on a union or professional register; (2) were waiting to be called back to a job from which they had been laid off; or (3) were waiting to report to a new wage or salary job within 30 days.

Labor force.--Persons are classified as in the labor force if they were employed as civilians, unemployed, or in the Armed Forces during the survey week. The "civilian labor force” is comprised of all civilians classified as employed or unemployed.

Not in the labor force.-- All civilians who are not classified as employed or unemployed are defined as "not in the labor force." This group who are neither employed nor seeking work includes persons engaged only in own home housework, attending school, or unable to work because of long-term physical or mental illness; persons who are retired or too old to work, seasonal workers for whom the survey week fell in an off season, and the voluntarily idle. Persons doing only unpaid family work (less than 15 hours) are also classified as not in the labor force.

Occupation.--Data on occupation are shown for the employed and relate to the job held during the survey week. Persons employed at two or more jobs were reported in the job at which they worked the greatest number of hours during the week. The major groups used here are mainly the major groups used in the 1960 Census of Population. The composition of these groups is shown in Volume I, Characteristics of the Population, Part I, United States Summary.

Data are also shown for four broad occupational groups (white-collar workers, manual workers, service workers, and farm workers), which represent combinations of the 11 major groups.

All persons engaged directly in agricultural production are classified as farm workers in this report. This included farm proprietors, managers, foremen, and laborers.

The nonagricultural group is subdivided into three groups. The white-collar group includes professional workers, proprietors, managers, and sales and clerical workers. The manual group

borers (other than farm); and the service category includes private household workers and other service workers.

Weeks worked in previous year.--Persons are classified according to the number of different weeks during the previous year in which they did any civilian work for pay or profit (including paid vacations and sick leave) or worked without pay on a family-operated farm or business.

Income.--For each person 14 years old and over in the sample, questions were asked on the amount of money income received in the previous year from each of the following sources: (1) Money wages or salary; (2) net income from nonfarm self-employment; (3) net income from farm selfemployment; (4) Social Security, veterans' payments, or other government or private pensions; (5) interest (on bonds or savings), dividends, and income from annuities, estates, or trusts; (6) net income from boarders or lodgers, or from renting property to others; (7) all other sources such as unemployment benefits, public assistance, alimony,

etc.

The amounts received represent income before deductions for personal taxes, Social Security, bonds, etc. If any amount was $10,000 or more, it was recorded as a specific amount wherever possible. It should be noted that although the income statistics refer to receipts during the previous year the characteristics of the person, such as age, labor force status, etc., and the composition of families refer to the survey date.

Total income is the sum of amounts reported separately for wage or salary income, selfemployment income, and other income. Wage or salary income is defined as the total money earnings received for work performed as an employee. It represents the amount received before deducting for personal income taxes, Social Security, bond purchases, union dues, etc. Selfemployment income is defined as net money income (gross receipts minus operating expenses) from a business, farm, or professional enterprise in which the person was engaged on his own

account.

Class of worker. --The data on class of worker are for persons who worked in the previous year and refer to the job held longest during the year. Persons employed at two or more jobs were reported in the job at which they worked the greatest number of weeks. The class-of-worker classification specifies "wage and salary workers" and "self-employed workers." Wage and salary workers receive wages, salary, commissions, tips,

or from a government unit. Self-employed workers have their own business, profession, or trade, or operate a farm for profit or fees.

Rounding of estimates.-- Individual figures are rounded to the nearest thousand without being adjusted to group totals, which are independently rounded. Percentages are based on the rounded absolute numbers.

SOURCE AND RELIABILITY OF THE ESTIMATES

Source of data.--The estimates are based on data obtained monthly in the Current Population Survey of the Bureau of the Census. The sample is spread over 449 areas comprising 863 counties and independent cities, with coverage in each of the 50 States and the District of Columbia. Approximately 50,000 occupied households are designated for interview each month. Of this number, 2,250 occupied units, on the average, are visited but interviews are not obtained because the occupants are not found at home after repeated calls or are unavailable for some other reason. In addition to the 50,000 there are also about 8,500 sample units in an average month which are visited but are found to be vacant or otherwise not to be enumerated.

The estimating procedure used in this survey involved the inflation of the weighted sample results to independent estimates of the civilian noninstitutional population of the United States by age, color, and sex. The independent estimates were based on statistics from the 1960 Census of Population; statistics of births, deaths, immigration, and emigration; and statistics on the strength of the Armed Forces. To these figures were added the members of the Armed Forces living off post or with their families on post and the institutional population. The estimated numbers of inmates of institutions shown in this report were obtained by assuming that the percent of the population who were inmates in each age and sex group in 1969 was the same as in the 1960 census.

Reliability of the estimates.--Since the estimates are based on a sample, they may differ

somewhat from the figure that would have been obtained if a complete census had been taken using the same schedules, instructions, and enumerators. As in any survey work, the results are subject to errors of response and of reporting as well as being subject to sampling variability.

The standard error is primarily a measure of sampling variability, that is, of the variations that occur by chance because a sample rather than the whole of the population is surveyed. As calculated for this report, the standard error also partially measures the effect of response and enumeration errors but does not measure any systematic biases in the data. The chances are about 68 out of 100 that an estimate from the sample would differ from a complete census figure by less than the standard error. The chances are about 95 out of 100 that the differences would be less than twice the standard error.

100,000,000...1,330,000

The reliability of an estimated percentage, computed by using sample data for both numerator and denominator, depends upon both the size of the percentage and the size of the total upon which the percentage is based. Estimated percentages are relatively more reliable than the corresponding estimates of the numerators of the percentages, particularly if the percentages are 50 percent or more. Table B contains the standard errors of estimated percentages.

Illustration of the use of table of standard errors.--Table 7 of this report shows that 12,458,000 males age 14 and over moved to a different house in the United States between March 1968 and March 1969. Table A shows the standard error on an estimate of this size to be approximately 300,000. The chances are 68 out of 100 that the estimate would have shown a figure differing from a complete census by less than 300,000. The chances are 95 out of 100 that the estimate would have shown a figure differing from a complete census by less than 600,000 (twice the standard error).

Of these 12,458,000 movers, 4,621,000, or 37.1 percent, moved to a different county. Table B shows the standard error of 37.1 percent of a base of 12,458,000 to be approximately 1.1 percent. Consequently, chances are 68 out of 100 that the estimated 37.1 percent would be within 1.1 percent of a complete census figure, and chances are 95

out of 100 that the estimate would be within 2.2 percent of a census figure, i.e., this 95 percent confidence interval would be between 34.9 and 39.3 percent.

Estimates of net migration between regions should be used with caution, as they are based on the difference between the number of out-migrants and the number of in-migrants for the region and have relatively large sampling errors. For example, table 13 of this report shows that in 1969 there were 70,000 migrants of Negro and other races moving into the West from other geographic regions, while during this same period 51,000 of these migrants moved out of the West. The apparent result is a net migration into the West of 19,000 Negro and other races.

Table A of this report shows the standard errors for estimates of 70,000 and 51,000 migrants to be approximately 20,200 and 17,200 respectively. The sampling error for 19,000, the difference of these estimates, is about 26,500. The chances are 68 out of 100 that an estimate based on the sample would show a figure differing from a complete census by less than 26,500. The chances are 95 out of 100 that the sample would show an estimate differing from a complete census by less than 53,000; that is, the 95 percent confidence interval for Negro and other races would include estimates of from 72,000 net in-migrants to 34,000 net out-migrants for the West.