Technical Appendix for 1992 QUALITY OF DATA Completeness of registration All States have adopted laws requiring the registration of births and deaths and the reporting of fetal deaths. It is believed that more than 99 percent of the births and deaths occurring in this country are registered. Reporting requirements for fetal deaths vary from State to State (see "Comparability and completeness of data"). Overall reporting is not as complete for fetal deaths as for births and deaths, but it is believed to be relatively complete for fetal deaths at a gestation of 28 weeks or more. National statistical data on fetal deaths include only fetal deaths occurring at a stated or presumed gestation of 20 weeks or more. Massachusetts data The 1964 statistics for deaths exclude approximately 6,000 deaths registered in Massachusetts, primarily to residents of that State. Microfilm copies of these records were not received by NCHS. Figures for the United States and the New England Division are affected also. Amended records for Alabama, Alaska, and New Jersey Numbers of deaths occurring in Alabama, Alaska, and New Jersey for 1992 are in error for all causes of death combined and for selected causes because NCHS did not receive changes resulting from amended records. An estimate of the effect of these omissions can be derived by comparing NCHS counts of records processed through the VSCP with counts prepared by the respective States as shown in table E. Differences are concentrated among selected causes of death, principally Symptoms, signs, and ill-defined conditions (ICD-9 Nos. 780-799) and external causes. Quality control procedures Demographic items on the death certificate--As previously indicated, for 1992 the mortality data for these items were obtained from two sources--photocopies of the original certificates furnished by the Virgin Islands and Guam and records on data tape furnished by the 50 States, the District of Columbia, New York City, and Puerto Rico. For the Virgin Islands and Guam, which sent only copies of the original certificates, the demographic items were coded for 100 percent of the death certificates. The demographic coding for 100 percent of the certificates was independently verified. - 1 - Table E. Numbers of deaths and ratios of deaths for selected causes as tabulated by State of occurrence and NCHS, 1992 [Data by place of occurrence include deaths of nonresidents. Numbers after causes of death are categories Ninth Revision, International Classification of Diseases, 1975] _____________________________________________________________________________ Ratio Causes Alabama NCHS AL/NCHS _____________________________________________________________________________ All causes........................... 39,068 39,107 1.00 Symptoms, signs, and ill-defined conditions...............780-799 957 1,034 0.93 Accidents and adverse effects ..........................E800-E949 2,098 2,078 1.01 Motor vehicle accidents ..........................E810-E825 1,136 1,094 1.04 All other accidents and adverse effects.........E800-E807,E826-E949 962 994 0.97 Suicide....................E950-E959 521 516 1.01 Homicide and legal intervention ..........................E960-E978 570 539 1.06 All other external causes..E980-E999 47 37 1.27 _____________________________________________________________________________ Ratio Causes Alaska NCHS AK/NCHS _____________________________________________________________________________ All causes........................... 2,319 2,307 1.01 Symptoms, signs, and ill-defined conditions...............780-799 39 65 0.60 Accidents and adverse effects ..........................E800-E949 355 421 0.84 Motor vehicle accidents ..........................E810-E825 125 109 1.15 All other accidents and adverse effects.........E800-E807,E826-E949 230 312 0.74 Suicide....................E950-E959 130 92 1.41 Homicide and legal intervention ..........................E960-E978 50 39 1.28 All other external causes..E980-E999 9 3 3.00 - 2 - Table E. Numbers of deaths and ratios of deaths for selected causes as tabulated by State of occurrence and NCHS, 1992 [Data by place of occurrence include deaths of nonresidents. Numbers after causes of death are categories Ninth Revision, International Classification of Diseases, 1975] _____________________________________________________________________________ Ratio Causes New Jersey NCHS NJ/NCHS _____________________________________________________________________________ All causes........................... 69,292 69,184 1.00 Symptoms, signs, and ill-defined conditions...............780-799 285 1,110 0.26 Accidents and adverse effects ..........................E800-E949 2,037 1,914 1.06 Motor vehicle accidents ..........................E810-E825 810 780 1.04 All other accidents and adverse effects.........E800-E807,E826-E949 1,227 1,134 1.08 Suicide....................E950-E959 591 492 1.20 Homicide and legal intervention ..........................E960-E978 415 382 1.09 All other external causes..E980-E999 179 44 4.07 _____________________________________________________________________________ As part of the quality control procedures for mortality data, each registration area goes through a calibration period, during which it must achieve the specified error tolerance level of 2 percent per item for 3 consecutive months, based on independent verification by NCHS of a 50-percent sample of that area's records. When the area has achieved the required error tolerance level, a sample of 70-80 records per month is used to monitor quality of coding. All areas providing data on computer tapes before 1992 have achieved the specified error tolerance; accordingly, the demographic items on about 70-80 records per area per month were independently verified by NCHS. The estimated average error rate for all demographic items in 1992 was 0.25 percent. These verification procedures involve controlling for two types of error (coding and entering into the data record tape) at the same time, and the error rates are a combined measure of both types. It may be assumed that the entering errors are randomly distributed across all items on the record, but this assumption cannot be made as readily for coding errors. Although systematic errors in coding infrequent events may escape detection during sample verification, it is probable some of these errors were detected during the initial period when 50 percent of the file was being verified, thus providing an opportunity to retrain the coders. - 3 - Medical items on the death certificate--As is true for demographic data, mortality medical data are also subject to quality control procedures to control for errors of both coding and data entry. Each of the 32 registration areas that furnished NCHS with coded medical information in 1992 according to NCHS specifications had to qualify for sample verification first. During an initial calibration period, the area had to demonstrate that its staff could achieve a specified error tolerance level of less than 5 percent for coding all medical items. After the area had achieved the required error tolerance level, a sample of 70-80 records per month was used to monitor quality of medical coding. For the 32 reporting States, the average coding error rate in 1992 was estimated at just over 4 percent. For the remaining 18 States, the District of Columbia, New York City, Puerto Rico, the Virgin Islands, and Guam, NCHS coded the medical items for 100 percent of the death records. A 1-percent sample of the records was coded independently for quality control purposes. The estimated average error rate for these areas was about 3 percent. The ACME system for selecting the underlying cause of death through computer application contributes to the quality control of medical items on the death certificate. (See "Automated selection of underlying cause of death.") The MICAR system automates the coding of multiple causes of death. The quality of the data produced by MICAR is better than the quality of the data produced using manual multiple cause-of-death coding (21). The version of MICAR used to process 1992 records processed about 88 percent of the mortality records with an average error rate of 0.33 percent on an underlying-cause basis and a rate of 0.58 percent on a multiple-cause basis. As part of the quality control procedures for using the MICAR data entry system, each registration area had to go through a calibration period as part of the initial training. During this period, the registration area had to demonstrate that its staff could achieve a specified error tolerance of less than 5 percent for coding all medical items based upon the MICAR data entry specifications. After the area achieved the required error tolerance level, a sample of 70-80 records per month were used to monitor the quality of MICAR coding. In addition, the sample records were also independently verified according to multiple-cause specifications. These verification procedures involve controlling for system error as well as coding and data entry errors on the records that were not automatically processed by the MICAR system. It is estimated that average error rate for all medical items was about 2.75 percent. Demographic items on the report of fetal death--As previously indicated, for 1992 the fetal death demographic data were obtained from two sources--coded records in electronic form from 20 registration areas and photocopies of the original certificate furnished by the remaining registration areas. For the 30 registration areas submitting photocopies, the demographic items were coded under contract by the U.S. Bureau of the Census. Coding and entering of information on data tapes were verified on a 100-percent basis because of the relatively small number of records involved. Quality control for state-coded data released for fetal deaths for 1992 was based on 100-percent comparison of data coded by the U.S. Bureau of the Census with the state-coded data. Allowable error was 2.0 percent. - 4 - Table F. Source for resident population and population including Armed Forces abroad: Birth- and death-registration States, 1900-1932, and United States, 1900-1992 ----------------------------------------------------------------------------- Year | Source --------------|-------------------------------------------------------------- 1992----------| U.S. Bureau of the Census, Electronic Data File, RESPO792, | and unpublished data. 1991----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 1095, 1993. 1990----------| U.S. Bureau of the Census, Unpublished data from the 1990 | census. 1990 CPH-L-74 and unpublished data consistent with | Current Population Reports, Series P-25, No. 1095. 1989----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 1057, 1990. 1988----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 1045, 1990. 1986-87-------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 1022, Mar. 1988. 1985----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 1000, Feb. 1987. 1984----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 985, Apr. 1986. 1983----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 965, Mar. 1985. 1982----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 949, May 1984. 1981----------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 929, May 1983. 1980----------| U.S. Bureau of the Census, U.S. Census of Population: | 1980, Number of Inhabitants, PC80-1A1, United States | Summary, 1983. 1971-79-------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 917, July 1982. 1970----------| U.S. Bureau of the Census, U.S. Census of Population: | 1970, Number of Inhabitants, Final Report PC(1)-A1, | United States Summary, 1971. 1961-69-------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 519, Apr. 1974. 1960----------| U.S. Bureau of the Census, U.S. Census of Population: | 1960, Number of Inhabitants, PC(1)-A1, United States | Summary, 1964. 1951-59-------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 310, June 30, 1965. 1940-50-------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 499, May 1973. 1930-39-------| U.S. Bureau of the Census, Current Population Reports, | Series P-25, No. 499, May 1973, and National Office of | Vital Statistics, Vital Statistics Rates in the United | States, 1900-1940, 1947. - 5 - Table F (cont'd). Source for resident population and population including Armed Forces abroad: Birth- and death-registration States, 1900-1932, and United States, 1900-1992 ----------------------------------------------------------------------------- Year | Source --------------|-------------------------------------------------------------- 1920-29-------| National Office of Vital Statistics, Vital Statistics | Rates in the United States, 1900-1940, 1947. 1917-19-------| Same as for 1930-39. 1900-16-------| Same as for 1920-29. ______________|______________________________________________________________ Other control procedures--After coding and entering on data tape are completed, record counts are balanced against control totals for each shipment of records from a registration area. Editing procedures ensure that records with inconsistent or impossible codes are modified. Inconsistent codes are those, for example, indicating a contradiction between cause of death and age or sex of the decedent. Records so identified during the computer editing process are either corrected by reference to the source record or adjusted by arbitrary code assignment (40). Further, conditions specified on a list of infrequent or rare causes of death are confirmed by the certifier or a State Health Officer. All subsequent operations in tabulating and in preparing tables are verified during the computer processing or by statistical clerks. Estimates of errors arising from 50-percent sample for 1972 Death statistics for 1972 in this report (excluding fetal death statistics) are based on a 50-percent sample of all deaths occurring in the 50 States and the District of Columbia. A description of the sample design and a table of the percent errors of the estimated numbers of deaths by size of estimate and total deaths in the area are shown in the Technical Appendix from Vital Statistics of the United States, 1972. - 6 -