Persons of native birth have been divided into two general groups and further subdivided under each of the two, as follows:

1. Native-born of native father.

Persons under this group are classified as White, Negro, Indian, Chinese, Hindu, Japanese, and Korean.

2. Native-born of foreign father.

Persons under this group are classified according to race of father in all tables where the data were secured for households, and according to country of birth of father in all tables where the data were secured for employees. Where classification is by race of father the classification used for several years by the United States Bureau of Immigration and Naturalization is followed.

Persons of foreign birth are classified according to race (or people). The classification of the United States Bureau of Immigration and Naturalization is followed.

In the study of households information is presented

1. By general nativity and race of the "individual" in all tables, which show facts which are personal in their nature, such as English speaking, occupation, or conjugal condition.

2. By general nativity and race of "head of family" in tables concerned with family matters-for example, family income.

3. By general nativity and race of "head of household" in all tables. dealing with living conditions, among which are tables showing the composition of the household and the number of persons per room and per sleeping room. The distinction which has been made throughout this study between "family" and "household" is dependent upon the use of the term "apartment."

An "apartment" is a room or rooms within which all the usual daily processes of living, namely, cooking, eating, and sleeping, are carried on by the occupants. According to this definition an apartment may be, for example, a whole house; or it may be a single room of what was originally intended as an apartment; or it may be a corner of a wareroom or the back of a storeroom partitioned off and set aside for household uses. Two or more groups of occupants with distinctly separate money interests frequently rent a number of rooms jointly, occupying certain rooms separately but sharing one or more, usually the kitchen, or kitchen and living room. Under these conditions neither the rooms used by the one group of occupants nor those used by the other can be considered an apartment, since the room used in common must in such case be considered a room in each apartment and thus be counted twice. Where these conditions have been encountered the entire number of rooms has been considered one apartment.

The "household" includes all persons living within an apartment, without regard to the relationships which exist among them. The household may consist of one or more families with or without boarders or lodgers; or it may consist of a group of persons living together, no family included; or it may consist of various combinations of families, "groups," and boarders or lodgers.

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The term "family" as used throughout these tables refers in general to the immediate family composed of husband, wife, and children. Groups of persons among whom none of these relations exist are not considered families. Households in which complicated relationships exist have been resolved into the component immediate families. Remnants of families maintaining a home are considered families when either husband or wife is present.

The general tables show results of two practically independent studies, as follows:

STUDY OF HOUSEHOLDS.

All tables headed "Study of households" are based on information from the schedule which was filled out for certain selected households in each of the several communities. Names and addresses were secured of employees in a given industry who were heads of households; and for each such household a schedule was filled out by an agent of this Commission who visited the apartment and secured detailed information, so far as possible, for every occupant, as well as data in regard to family and household organization and status at the time of the visit.

STUDY OF EMPLOYEES.

The general tables headed "Study of employees" present data from the schedule relating only to the individual employee. This schedule was filled out by the employee himself or by some one, detailed by the employer to the task, to whom the employee furnished data.

The general tables of this series, therefore, concern only the history and present status of the employee, while the other series, as has been stated, presents data not only for certain of the employees, but also for members of their households. All data included under the "Study of employees" are tabulated by sex and by the general nativity and race of the individual. For the native-born of foreign father the classification is by country of birth of father and not by race of father.

DESCRIPTION OF TABLES.

Total number of households and persons studied, by general nativity and race of head of household: Study of households. Tables 1, 51, 101, 150, and 200.-These tables enumerate the households studied of each race, the aggregate of the members of the households of each race, and the persons, male and female, for whom detailed information was secured. All members of households appear in these tables under the general nativity and race of head of household.

Number of persons for whom detailed information was secured, by sex and general nativity and race of individual: Study of households. Tables 2, 52, 102, 151, and 201.-These tables are a second enumeration of the persons, male and female, who are included in the detailed study of members of households. In this enumeration each individual appears under his own general nativity and race.

Total number of male employees for whom information was secured, by sex and general nativity and race: Study of employees. Tables 3, 53, 103, 152, and 202.-These tables enumerate the employees for whom data were secured for the "Study of employees." The enumeration is by general nativity and race of employee.