Persons who speak a language other than English at home were asked to report the language spoken, as well as their proficiency in English (see Language Usage and Ability to Speak English). This item was asked on a sample basis.
Respondents were instructed to report the language spoken most often, for persons speaking two or more non-English languages at home, or the first language learned, where the language spoken most often could not be determined.
The write-in entries of the language spoken were coded in census processing offices into 387 categories which arerecorded on basic records and public-use microdata files. Tables in PC30-1-C reports include the following categories:
English only, Chinese, French, German, Greek, Italian, Philippine languages, Polish, Spanish, other specified language, and unspecified language.
Data on languages spoken in the home are typically presented separately for persons 5 to 17 and 18 years old anti over. These data should not be interpreted as the number of people who are able to speak specified languages, since this question counts only persons who speak a language other than English at home.
The reported number of persons who speak a language other than English at home may be inflated slightly by a processing error. The total number of persons who speak a language other than English is inflated by approximately 0.4 percent nationwide. There is some geographic variation in the frequency of the errors, but no substantial spatial clustering has been discovered. Subsequent data products (STF 4, STF 5) will correct these errors, and thus may disagree with the estimates provided in STF 3.
These data on current language are not comparable to questions asked in 1950 and 1970 on mother tongue, i.e., language other than English spoken in the person's home when he or she was a child. In 1970, Spanish mother tongue was a major determinant in the classification of "persons of Spanish heritage."
See also: "Language Usage and Ability to Speak English".