Description

CLRBLINDNOWC indicates whether the person now has chronic color blindness. This variable is created with supplemental programming by the IPUMS NHIS staff from the pre-1997 condition records. For general information about IHIS variables (such as CLRBLINDNOWC) created from the pre-1997 condition records, see the User Note on Condition Records and Condition Variables.

Defining Color Blindness Records and Identifying Persons with Color Blindness

For all available years, persons who were asked a direct question about having color blindness and who have a chronic color blindness condition record are given a "Yes" code for CLRBLINDNOWC. Persons who were asked a direct question about having color blindness but do not have a chronic color blindness record are given a code of "No." Persons who were not asked a direct question about color blindness, or for whom it is unknown whether they were asked such a question, are given a code of "NIU" (not in universe), regardless of whether they have a chronic color blindness record.

For 1971, 1977, and 1978, chronic color blindness records were defined as those condition records with a code of "3773" ("Color blindness") in the variable DCICDCOD in the original NHIS public use files. This condition code value comes from the International Classification of Diseases (ICD) Revision 8. Additionally, to be considered "chronic," color blindness condition records must have a code of "1" ("Chronic") in the variable CACODE in the original NHIS public use files.

For 1979 to 1981, chronic color blindness records were defined as those condition records with a code of "3685" ("Color vision deficiencies") in the variable DCICDCOD in the original NHIS public use files. This condition code value comes from the International Classification of Diseases (ICD) Revision 9. As with previous years, to be considered "chronic," color blindness condition records must have a code of "1" ("Chronic") in the variable CACODE in the original NHIS public use files.

For 1982 to 1996, chronic color blindness records were defined as those condition records with a code of "239" ("color blindness") in the variable C1CONDRC in the original NHIS public use files. This condition code value comes from NCHS's Diagnostic Recode C: Chronic Conditions and Impairments.

Weights
For 1971 and 1977, CLRBLINDNOWC should be weighted with PERWEIGHT.

For 1978 to 1981, CLRBLINDNOWC should be weighted with CONDWT4.

For 1982 to 1996, CLRBLINDNOWC should be weighted with CONDWT2.

Comparability

As with all of the person-level condition variables created by IHIS from condition records prior to 1997, the universe for CLRBLINDNOWC is substantially different for 1978 forward than it is for years prior to 1978. Beginning in 1978, only persons living in 1/6 of households, rather than all persons, were asked a direct question about currently having color blindness. This change requires that different weight variables be used depending on which years of data are analyzed. See the "Description" tab for details.

Additionally, there is a change in the way "Yes" responses are coded over time. See the User Note on Condition Records and Condition Variables for details about the composite coding scheme employed by IHIS.

Universe

Availability

• 1971, 1977-1996

Weights

• 1971, 1977 : PERWEIGHT
• 1982-1996 : CONDWT2
• 1978-1981 : CONDWT4