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.

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 14 years old and over classified as employed or unemployed.

Paid labor force. Persons are classified in the paid labor force if they were employed as wage and salary workers or self-employed workers during the survey week or were looking for work at the time and had last worked as wage and salary or self-employed workers.

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 labor-management 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 religious, charitable, and similar organizations.

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.

Occupation. The data on occupation of employed persons 14 years old and over refer to the civilian 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 occupation grouping used here are mainly the major groups used in the 1970 Census of Population. The composition of these groups is shown in the 1970 Census of Popualtion, Volume I, Characteristics of the Population, chapter C. The categories used are combinations of detailed classifications.

Four occupation divisions. The major groups of Occupations are arranged in four divisions as follows:

White collar.-Professional, technical, and kindred workers; managers and administrators, except farm; sales workers; and clerical and kindred workers.

Blue collar.-Craft and kindred workers; operatives, including transport; and laborers, except farm.

Farm workers.-Farmers and farm managers, farm laborers and farm supervisors.

Service workers.-Service workers, including private household workers.

The sequence in which these four divisions appear is not intended to imply that any division has a higher social or skill level than another.

Year-round full-time workers. A year-round fulltime worker is one who worked primarily at full-time civilian jobs (35 hours or more per week) for 50 weeks or more during the preceding calendar year.

Income. For each person in the sample 14 years old and over, questions were asked on the amount of money income received in the preceding calendar year. Although the income statistics refer to receipts during the preceding year, the characteristics of the person, such as age, labor force status, etc., and the composition of families refer to the time of the survey. The income of the family does not include amounts received by persons who were members of the family during all or part of the income year if these persons no longer resided with the family at the time of enumeration. On the other hand, family income includes amounts reported by related persons who did not reside with the family during the income year but who were members of the family at the time of enumeration.

Number of earners. This number includes all persons in the family with $1 or more in wages and salaries, or $1 or more or a loss in net income from farm or nonfarm self-employment.

Poverty status. Families and unrelated individuals are classified as being above or below the poverty level, using the poverty index adopted by a Federal Interagency Committee in 1969. This index provides a range of income cutoffs or "poverty thresholds" adjusted to take into account such factors as family size, sex and age of the family head, the number of children, and farm-nonfarm residence. The poverty cutoffs for farm families have been set at 85 percent of the nonfarm levels. These income cutoffs are updated every year to reflect the changes in the Consumer Price Index. The average poverty threshold for a nonfarm family of four was $5,500 in 1975. For a detailed explanation of the poverty definition, see Current Population Reports, Series P-60, No. 103, "Money Income and Poverty Status of Families and Persons in the United States: 1975-1974 Revisions."

Median. The median is presented in connection with the data on age, years of school completed, and income. It is the value which divides the distribution into two equal parts, one-half of the cases falling below this value and one-half of the cases exceeding this value.

Mean. The mean (average) is presented in connection with data on number of persons per family, income of persons, and income of families. The mean number of persons per family is the value obtained by dividing the number of persons having

the characteristic under consideration by the appropriate number of families. The mean income is the amount obtained by dividing the total income of a group by the number of persons, or families, in that group.

COMPARABILITY OF DATA

WITH THE 1970 CENSUS

An estimate of 9.1 million persons of Spanish origin was obtained from the 1970 Census of Population, compared with an estimated 11.1 million persons of Spanish origin obtained from the March 1976 CPS. This difference between the 1970 census and the March 1976 CPS estimates of persons of Spanish origin occurred mostly because of:

1. Survey procedures. Although the 1970 census used both self-enumeration and direct interviews to collect data on persons of Spanish origin, the March 1976 CPS was done entirely by direct interviews (much by telephone).

2. Mexican origin categories. The 1970 census question on Spanish origin had only one category denoting Mexican origin, whereas the March 1976 CPS had four categories for Mexican origin.

3. Determining origin of children under 14 years old. In the 1970 census the respondents themselves determined whether their children under 14 years old were or were not of Spanish origin. In the March 1976 CPS, children under 14 years old in a household were classified as of Spanish origin if either the household head or his wife was of Spanish origin.

4. Sample size and variability. The 1970 census information on persons of Spanish origin was based on a sample of 5 percent of the population; the March 1976 CPS information was based on a sample of about 1 in 800 persons. Sampling variability, therefore, also affected comparability of data for persons of Spanish origin between the 1970 census and the March 1976 CPS. .

5. Population growth. Growth of the Spanish population is another reason why the 1970 census estimate of the number of persons of Spanish origin differs from that of the March 1976 CPS. Although birth, death, and migration data on persons of Spanish origin are not available nationally, nor can

these data be, at present, precisely estimated, rough computations indicate an approximate rate of natural increase (excess of births over deaths) of about 1.8 percent per year or 10.8 percent for the period between 1970 and 1976. Furthermore, net immigration from abroad could also have contributed significant growth. For example, in the 6-year period ending June 30, 1976, about 670,000 immigrants were admitted to the United States from all Spanish-speaking countries as permanent residents. Thus, all told, population growth for the period from April 1970 to March 1976 may account for four-fifths of the difference between the 1970 census and the March 1976 figures; and the balance in the difference, accounted for by the reasons noted above.