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SS,~IES 4-2 HEALTH STATISTICS FRO,¥ THE If. S. ,%~ATIOgAL HEALTII SURVEY~ ~he statistical design of the Health Household-Interview Survey by staff of the $. National Bealth Survey and the Bureau of the Census U. S. DEPARTHENT OF HEALTH, EDUCATIOH, AND WELFARE Harion B, Folsom, Secretary Public Health Service Leroy E. Burney, Surgeon General Division of Public Health Hethods Wil]iz~ H. Stewart. H. D.,Chief III Washington, D. C. July 1958 Tl06653812

IU. S. NATIONAL HEALTH SURVEY Forrest E. Linder, Ph.D., Director Theodore D. Woolsey, Assistant Director Alice M. Waterhouse, M. D., Medical Advisor Walt R. Simmons. Statistical Advisor O. K. Sagen, Ph. D., Chief, Special Studies Philip S. Lawrence, Sc. D., Chief, Household Survey Analysis Margery R. Cunningham, Staff Assistant The U. S. National Health Survey is a continuing program under which the Public Health Service makes studies to determine the extent of ill- ness and disability in the population of the United States and to gather related i~ormation. It is authorized by Public Law 652, 84th Congress. (:O-OPERATION OF THE BUREAU OF THE CENSUS Under the legislation establishing the National Health Survey, the Public Health Service is authorized to use, insofar as possible, the services or facilities of other Federal, State, or private agencies. For the national household survey the Bureau of the Census designed and selected the sample, conducted the household interviews, and processed the data in accordance with specifications established by the Public Health Service. Public Health Service Publication No. 584-A2 TI0~653B13

PREFACE This report presents a description of the initial statistical design of the continuing Health Household-Interview Survey, which is a major phase of the program of the U. S. National Health Survey. The design described inthis report is that used during the period, July-December [957, which, with minor modifications, will be used throughout 1958. Except for such modifications, the design is, therefore, the basis of the sta- tistical reports being published from the household interviews conducted during this period. General requirements for the survey design were pre- pared by the Public Health Service and on the basis of these, the theoretical and operating plan of the sample was prepared by th~ staff of the Census Bureau. Although there are some important differences, the sample plan for this health survey draws heavily from designs previously developed by the Bureau of the Census for its Current Population Survey. In addition to its function as the principal designer of the survey sample plan, the Census Bureau also conducts the field interviewing, and processes the data in accordance with spec- ifications provided by the Public Health Service. Tabulation is handled on the Census Bureauts electronic computers. Final tables and published reports are planned and prepared by the Public Health Service. Principal responsibility for development of the statistical design and preparation of the text of this report was shared by William N. Hurwitz, Harold Nisselson, Walt R, Simmons, Joseph Steinberg, Joseph Waksberg, and Theodore D. Woolsey. (Messrs. Simmons and Woolsey are members of the U. S. Na- tional Health Survey staff; Messrs. Hurwitz, Nisselson, Stein- berg, and Waksberg are staff members of the Bureau of the Census.) They were assisted by numerous members of the Census Bureau staff, including especially Katherine G. Capt. Robert Ho Finch, Jr., Mary J. Jaracz, Garrie Jo Losee, and Helen M. Lucas. TI06653814

STATISTICAL DESIGN OF THE HEALTH HOUSEHOLD-INTERVIEW SURVEY 1. INTRODUCTION The program of the U. S. National Health Sur- vey is a statistical measurement of the extent of illness, disability, and related conditions of the population. This program consists of several dis- tinct but related parts. One of these is the collection of data on health through a continuing Health House- hold-Interview Survey. A second main part of the program is a series of surveys which utilize pro- cedures other than household interview as the source of data on health. A third phase of the pro- gram evaluates procedures and results and devel- ops improved techniques of measurement. The present report describes the statistical design of the ftealth Household-Interview Survey. In addition to setting forth the pattern of the Survey as it was initiated in Jdy 1957 and as it functioned in its first year of operation, the report will em- phasize two further points. One is that the house- hold interviews, while independent in a statistical sense of other surveys in the program, are but one very important component of the broader under- taking which is the U. S. National Health Survey (NHS), The second is that the "hdusehold survey constitutes an evolutionary program which may be expected to change as experience accumulates and which, at any given time, is expected to fulfill only those objectives of the National Health Survey for which it is the most appropriate vehicle. Substantive findings from the household-inter- view survey are being published by the Public Health Service in a sequence of numbered docu- ments identified as Health Statistics. Series B. Technical reports and methodological studies are issued in Series A, and include this report on sta- tistical design, Arrangement of material in the present re- port is intended to facilitate use by two different groups of readers. It is hoped that the body of the report will be of interest to and readily readable by all professional persons coneernod with health problems and those interested in research methods. Several technical appendices have been added for the benefit of statisticians, but contain material which may be informative for a wider audience. 2. BACKGROUND AND OBJECTIVES History A detailed account was given in the first pub- lication in this Series t, of the background, need for, purposes, and expected product of the U. S. National Health Survey. That story will not be du- plicated here. However, it may be helpful to recall very briefly a few highlights of the period which preceded initiation of the operating program in the middle of 1957. By 1957 it had been more than 20 years since thelast major survey to obtain comprehensive sta- tistics on diseases, injuries, and impaixments in the general population of the United States. Carried out in 1935-36, that survey was a major project in which 737,000 urban households were visited by interviewers to obtain data on morbidity, impair- ments, and health characteristics. It remains a landmark in the field. In the years since 1936 there have been a num- ber of community studies of morbidity, prominent among which are the names of Hagerstown and Baltimore, Md.; Pittsburgh, Pa.; Hunterdon County, N. J.; Kansas City, Mo.; New York Cit~,; and Cali- fornia (both San Jose and a statewide study). These T106653815

~tubie~. as well as ozcasional emferimmnts with me~.J is ~le of pro~J~g injuries [oge~r %~th rela~ i~o~adon &uch as ~e accompany~g lo~s of ~ ~om work or o~er u~ual acd~J~es. ~ Janus., 1949, ~e U. S. NatlonM Com~ee on VitM and Heal~Statisdcs was established. Sub- committees were established in ~cem~r 1949 and ~to~r 1950 to study the needs for current mor- bi~ty sta~sdcs. As a res~ of lhe~ recommenda- tions, a third S~¢o~ttee was established in Februa~ 1951 under ~e chaima~s~p of Dr. W. ~urber F~es of Jo~s HopMns Univ~rsi~, and instructed to draft a "Plan fern nation~ surveykeepinginview~e interests ofl~al ar~s." After ~reful study, t~s S~co~ittee recom- mend~ that several s~eps be taken, and in ~rtic- ~ar: "~at a condn~ng na~onal morbidity survey ~ conducted .... ks pu~ose would he ~o obtain data on the prevalence and ~cidence of disease. injuries, and impairments, on the nature and du- ration of the resulting disability, and on the amoun~ and type of mescal care received. ~e data wouid ~ obtained from a probability sample of house- holds" (page 28 of reference i). Public Law 652 and NHS Objectives In the summer of 1955, the Department of Health, Education. and Welfare proposed legisla- tion for a continuing health survey, closely paral- leling recommendations of the Subcommittee, The proposal was included in the President's recom- mendations on health matters, received bipartisan support in Congress, was enacted into Public Law 652, 84th Congress. and was signed by the Presi- dent on July 3, 1956. Later the same month appro- priations were made available for planning and pretesting during the fiscal year ending June 30, 1957. The law authorizes the Surgeon General of the Public Health Service to make continuing surveys and special studies of the population of the Urtited States to determine the extent of illness and disa- bility and related information suchas: the number, age. sex, ability to work or engage in other activi- ties, and occupation or activities of persons af- flicted with chronic or other disease or injury or handicapping condition; the type of disease or in- jury or handicapping condition of each person so afflicted; the length of time that each such person has been prevented from carrying on his occupa- tion or activities; the amounts and types of serv- ices received for or because of such conditions; and the economic and other impacts of such con- ditions. A sigmificant feat-are cf PubLic Lay; 652 is that it not e:Lly provides ~at s~.d:srantive data h_ bled, but in additicn, directs th~ Public Health S~'ice. "to develop and test hey, or improved mer/-tcd3 for chtaining current data cn illness and disabilitT and related information." Thus legislative intent Ic-~ks to the establish- menz of health statistics as noted in the law. and foresees "... continuing surveys ... spqcial stud- ies... [and] develop ling] a.d test ling] new and improvcd methods" as the objectives of the U, S, National Health Survey. Planning and Pretesting the Household fnterv'iews Throughout the fiscal year ending in June 1957 plans were developed for organizing and carrying out the household survey which had been contem- plated by the Subcommittee and authorized by Con- gress. The law contained the provision whereby the program could secure the assistance of other Fed- eral agencies, as well as private persons or agen- cies, in carrying out its responsibilities. Under this provision, the NHS made arrangements to uti- lize the very extensive resources and experience of the Bureau of the Census in planning and con- ducting the household-interview .survey. From the beginning, it was clear that the N~- tional Health Survey should be a general mttItipur- pose undertaking, rather than a study with some single specific limited objective. This concept meant that presurvey planning was particularly important. It required a careful review of previous efforts, a weighing and evaluating of a large number of possible alternatives, so that the new survey might be sufficiendy comprehensive to cover many of the desired objectives, while at the same time not to be so diluted as to deal inadequately with all topics, By February 1957, general structure of the survey had been determined, samples had been drawn, and a tentative questionnaire and field in- structions had been drafted. A pretest of 1,200 households was condt/cted in Charlotte, N, C,, to provide a complete field trial of procedure. The pretest was used alsofor training field supervisors for the national program, The next month was de- voted topolishing the questionnaireand procedures, and to hiring and training interviewers, In the 2 months of May and June, the entire nationwide or- ganization went through a shakedown and araiuing period with interviewing and editing proceeding just as though the survey were in operation. Of- ficial collection of data began the first week in July 1957. TI08653816

3. SUMMARY OF STRUCTURE OF HEALTH HOUSEHOLD-INTERVIEW SURVEY Role of Intervlew Survey. As noted in the previous .~ection, the program of the U. S. National Health Survey is intended to be an intensive and sustained undertaking to pro- vide morbidity and health statistics, utilizing what- ever resources andmethods are appropriate to the task. Tt~e program is expected further to evaluate existing sources and methods and to develop new methodologies. Among possible sources of data a prominent position goes to medical and health records. These include such originating places as hospitals, physi- cians' and dentists' offices, and insurance records of several kinds. They include, too, reporting under governmental regulation of certain types of mor- bidity and mortality, and especially the filing of death certificates. Another potentially significant source of in- formation may lie in samples of persons who are given clinical tests and measurements or general health or medical examinations. All these sources, and others, are to be ex- plored by the NHS. Several pilot projects in these areas already have been initiated. However, a considerabl~ body of opinion con- siders the household interview as one of the most promising sources of data on health. There are limitations to the accuracy of diag- nostic and other information collected in household interviews. For diagnostic information the house- hold respondent, can, at best, pass on to the inter- viewer only the information the physician has given to the family. For conditions not medicallyattended, diagnostic information is often no more than a de- scription of symptoms. However, other types of facts, such as those concerning t.he circumstances and consequences of illness or injury and the re- suiting action taken or sought by the individual, can be obtained more accurately from household members than from any other source since only the persons concerned arc in a position to report all of this type of information. Furthermore this type of survey facilitates greatly comparison of the ill population and the well population, and as- sessment of relative impacts of a variety of ill- nesses and impairments. The Health Household- Interview Survey described in this report is the vehicle being used by the U. S. National Health Survey to produce data presently believed to be most appropriately obtained from members of the household. Evolutionary Pattern Continuity and comparability of estimates for different time periods are desirable objectives, and will be given attention in the interview survey, especially when changes are proposed but they will not have overriding priority. A substantial portion of resources and energy of the NHS, at least dur- ing its early years, is to be devoted to studies and evaluation of quality of data input, to efficiency of collection and processing, and to usefulness of out- put. It is expected that these activities, augmented by the active and constructive criticism of users. will lead to a program which is changing in re- sponse to need in scope, content, method, and spe- cific product. Although the interview survey has only had 1 full year of operation, already changes have been made in sample design, questionnaire, and collec- tion and processing procedures. The description given in the follo~ving pages is in all major re- spects that which was in effect through the first year of operation, although minor changes occurred from one quarter to another. Quantitative refer- ences suchas sample sizes and noninterview rates apply for the most part specifically to experience in the first 2 quarters of operation. The Questionnaire The questionnaire is a 9-part document which is handled by the interviewer rather than the re- spondent, and on which the interviewer transcribes replies of.the respondent. Most replies can be re- corded by checking proper boxes on the form. The text of the questionnaire is supplemented by6 check list cards which are shown to the respondent at appropriate points in the interview. The check lists clarify certain questions so as to aid the respond- ent in understanding types of answers required and in recalling specific experiences. Physically, the questionnaire is of the hook type, providing separate columns for each of 7 possible members of a household. If a household contains more than 7 members, more than 1 ques- tionnaire is used. A facsimile of the questionnaire is contained in Appendix I. It is planned that items on the questionnaire may be divided into 2 groups--not separately ex- T108653817

i-/hited in the prem~ format. 0~ group efa core of ~asic quz$~ns w~ch ,~I ~e re~a~d ~n rela~vely unchanSed fo~ over an exTen~ ~od ~f tim~. ~e me~nd ~oup consists of sup- plemenm~' questions which will ke inclul~ ~em- psra~ly for blccks o[ I or a few ~len~r quar- ters. ~s general plan provides for ~e of re~ar se~es of ~sic stads~cs, and at same time ~e~its fle~flity in secu~ng oc~- sional measures of a %~der class of phenomena. As initially used, ~e questionnaire ca~ies 40 items for identification of households and persons and soci~cono~c desc~pdon of respondents. (A question to which the inter%ewer must secure an answer is interpret~ as one item in this count. ~e same inte~retation applies in ~e following counts.) It includes 12 general questions on presence or absence of illness, accidents, ~ir- ments, or con~tions for each member of the house- hold, and 54 detailed questions for each ~rson-- for whom the questions are appropriate--on de- tails of illnesses, accidents, and impairments, and on m~ical, dental, and hospital care. For most questions, the re~ll peri~ is the previous 2 weeks. But for some items of lo~v incidence, for which memo~ is reliable, such as hospitaliza- Oons, the recall exteads over the year pre~ous to the interview. Interviewin~ is conducted in the home, when- ever possible with the in~vidual person if over years of age, and otherwise with a responsible adult mem~r of the family. A separate report on the questionnaire is in preparation. It will trot more thoroughly the def- initions, concepts, scope, and content of ~e sched- ule. In addition, each report issued on a substantive h~Ith topic trots that part of the questionnaire w~ch applies most directly to ~e topic under study. Sample Design, Survey Methods, and I:stimation The sampling plan of the survey follows a high- ly stratified multistage probability design which permits a continuous sampling of the civilian pop- ulation of ~- United States. The first stage cf the de~i~n coasists o5 an area sample of 372 from among ahzut 1,9~0 geo~aphi~lly de~ned p~m~" s~ ~ts (PSU's) into whi~ the con~nen~l U~ted States has been ~Sded. A PSU is a counD', a ~oup of cen~guous counties, or a Stan~rd ropolitan Ar~. With no lo~s in general undersmn~ng, the main~g sta~es~wl~ch consist of a s~ies ~f sam- plings of successively smiler parcels of land-- can he telescoped and treated at this point in the report as an ~t~ate stage. Within PSU's then, d~mate-stage ~its called se~ents are defined, also ge~raphically, in such a manner that ~ch segment contains an expected 6 households in ~e sample. For each week a random sample of about 120 se~ents is drawn. Persons in the appro~- mately 700 households in those segments areinter- viewed conceding illnesses, injuries, chronic con- ~dons, disability, and other factors retated to health. Household members interviewed each week are an independent representative sample of the pop- ulation, ~o that samples for successive weeks can be combined into larger samples for, say, a calendar qua~er or a year. Thus, the desi~ permits both continuous measurement of characteristics of high incidence or prevalence and, through the larger consolidated samples, more detailed analysis of less common characteristics and smaller cate- gories. The national sample plan over a 12-month peri~ includes appro~mately 115,000 persons from some 36,0~ households in a~ut 6,000 segments, wi~ representation from every state. The desi~ is such that tabdaOons can ~ provid~ from the annual sample for various geographic sections of • e United States and for metropolitan, urban, and rural sectors of the Nation. Estimation is accomplished by a technique wMch insures that sample results are consistent with official Census Bureau estimates of current population by age, sex, and color, and which se- cures si~ificant reductions in sampling variance. Tec~ically, ~is pr~edure is a 2-stage ratio e~- Omation. Subsequent sections in the b~y of this report and in the Appendices descri~ leading fea- tures of the design ~n greater detail. 4. SURVEY PROCEDURE Collection of Data Data are collected through a household inter- view. Over the Nation there are 120 interviewers, trained, directed, and guided by 17 supervisors located in Census Bureau Regional Offices. The 4 supervisors are career Civil Service employees whose prime responsibility is the National Health Survey. They have administrative and clerical support from the Census Bureau field organization, and direct technical guidance from a Health Sta- tistics Branch in the Washington office of the Cen- sus Bureau. T106653818

Tn-~ inter'dewers (initially aH ~'om~) are gar~-tim~ employee~, selected through an exami- nation and ~es~n~ p~ce~s ~]~ch is a~i~stered hy ~e suF~isors, accor~n~ to ~ec~ons set ~ ?;as~ton. ~e ~c~t of work done ~y an in- ~e~;ie~er v~es deFen~ en densi~" of ~ sam- p~e n~r her home london. A ~i~l inte~iewer m~y have 26 assi~ents in a }~r, or an average of I assi~t each 2 ~eeks. Usually an assi~- meat consists of ~e~iews in appro~mately 12 households. Inclu~g trai~n~. ~avel, and call ~cks, ~he ~yp[cal ~ervle~er is employed an aver- a~e of 12 ho~s per week. Trai~n~forbo~ su~rvisors and~erviewers is a pr~ess for ~prov~ and con~ollin~ ~e inte~iew and dam from it. As such, it is a pro- cedure, par~s of which mus~ con~nue throughout ~e life of the su~ey, and is not an ac~ivky which co~d ~ completed at ~he ~i~in~ of ~e opera- dons. ~e su~rvisor is ~iven 5 ~nds of trainin~ ~yond ~e Ci~l Se~ce requirements for sppoin~ent ~o ~e job. First, the su~isor is supplied wi~ written ~ck~ro~d m~terials se~tin~ fo~h ~e objectives, and pu~eses of ~e ~dertakin~. Sim- ~arly he is ~iven demil~ inspections cove~n~ every aspec~and i[em of field operations. He s~ud- ies the materials, d~s practice exercises, sad rakes written examina~ons. ~e second bl~k of ~rainin~, for [he firs~ ~roup of supe~isors, was participation for2 weeks ih ~e dress-rehearsal pretes~ of the su~ey which t~k place in Charlotte. Replacements have simi- ]at experiences while se~in~ as understudies another supe~isor. ~e ~hird type of trainin~ comes from the condnuin~ flow of written instructions and corre- spo~ence, and of evaluations of ~ormance ou£from Washington. ~e latter come from quality- control sad q~lity-checkin~ operations pe~orm~ in Washington as psr~ of ~he edidn~ processes. Twice a year (3 dines the first year) super- ~sors over ~he Nation are assembled for a 2-day review of pr~ram objectives, new developments, and selected proc~ursl problems. ~ese sessions permit, of course, a helpful exchange of ideas amon~ supervisors sad between the field super- visors and the Washin~on staff. Finally, ~e supervisor has the advantage of condnuin~ experience since his regular job includes • e ~rsinin~ of interviewers, obse~adon of inter- ~ewiu~ for new inte~qewers, and personally re- in[erviewin~ a s~sample of households as a of ~he quali~y-conzrol pr~ram. As sta~ed above, ~he prospective in[erviewer is selected ~hrou~h a pr~ess of e written e~m- ina~on and testin~ of ~enersl ~eHi~ence and for apzRude for su~ey operations w~ch she wo~d exacted to pe~orm. ~e new in~e~iewer is @yen a 5-day initial co~se of ~ainin~. ~is course consists of 5 ~y~s of activity: (I) Instruction from a field ~z~rvisor on ~u~os-= and ge=~ral charac- teristics ~f~e s~:ey. (2)A demiled Fage-~--~age te~be~%er and su;e~-issr go ~ou~ aH ~c- d~n~ mate~al ~c~e~er. (S) ~as~reom Frac~ce Exercises. ~ %Td~ ~e ~te~ewer solves ~Ti~en proble~ and %~dth ~e ~sor de~e~es correct a~w~rs--~ese are exercises ra~r than zests, and ~y ~he inte~Jewer defi~tely how we~ she has succe~. (4) Home assi~ents which also are ~en answers problems, which are ~eat~d more in ~e ~ure of tests sad ~ w~ch res~ are ~scuss~ by inter- ~ewer s~ su~isor. (5) Practice in households ~der directperso~l obse~;adon by ~he supervison ~e s~udyofins~cdons, ~he prac- tice exercises, and ~he home assi~ents are ~s- ~rib.Zed ~rou~hout the 5-day peril. If ~e pros~cdve ~ze~iewer successfully completes ~e tr~nin~ course, she ~ins opera- tional inte~ie~in~, her firs~ assi~en~ ~rried out a~in ~der ~rec~ person~ observa- tion by ~e supervisor. After sppro~stely 1 month, a new ~er- viewer is ~v~ f~her Home Assi~me.~s which a~ain are ~aded and discussed, if neces~ry, by the supe~isor. Subsequently, in co--on wi~ inte~iewers, she spends 2 hours each month on such assi~men~s. Each quarter the supe~isor recon~acts abou~ one sixth of ~he households in his par~ of the sam- ple. He audits ~he household informa~on obtained ~rlier and reinte~ie~s indepe,dendy one predes- i~sted me~r of the household. He compares • fferences ~veen the ~ointe~iews and attempts to de~e~ine w~ch i~orms~ion is correct. ~ese rein~e~iews are randomly dis~ribut~ amon~ the in~e~iewers ~der his supervision so ~ha~ control charts based on s~ut5 percent of sn interviewer's work can ~ maintained. Each ~eek, as a par~ ~he editin~ pr~ess in Washington, error rates are calculated separately for ~ch ~te~iewer's work. ~ese are ~ansmit~ed ~o the appropriate su~r- ~sor for his use in further trainin~ and in ti~ht- e~n~ control over ~he In~ervIew process. Two or t~ee times each year, ~roups of in- reviewers are assembled et Ke~ionsl ~ices for I- or 2-~y refresher co~ses on objectives, mesh- es, proc~ures, and special ~ures of ~he sur- vey. After a household has been selected ~or the sample. ~ "Dear Fried" letter, si~ned by ~he rector, Bureau of ~he Census (fi~. I). is addressed and a few days ~fore [he exacted ~te~iew mailed to the household. This letter is intended ~o ~ s ~eneral in~ucdon ~o ~he su~ey, to have ~ect of addin~ o~cial ssnc~on to i~, and ~o make i~ somewhat ~sier for the in~e~[ewer to secure sn au~ence. ~ no precise address is ~o~, ~his 9tep is fore~one. Wan ~e Mte~ewer a~ives at the household, after s ve~, brief ~ucdon, she he~ns imme- T106653819

Form-hq-IS-6C4) (4-26-57) F~A~MF_NT (D~" COMMKI:ICt=" WASHIN~TON 25 6 D~ar Friend: The Bureau of the Census has been asked by the Public Health Service to act as its agent to carry out a survey to obtain information about illnesses, diseases and injuries among residents of this area. The survey is one part of the National Health Survey Program which Congress recently authorized because of the need for up-to-~late sta- tistics on the health of our people. Physicians, research workers, and other ~roups in health fields are much interested in the knowledge which will be gained from this survey. Every month several thousand addresses are chosen to give a cross-section of the whole United States. and the people at those ad- dresses are interviewed to obtain the necessary information. This month the address of your dwelling place is one of those chosen, and you will be visited by a Census Bureau interviewer within the next week or two. The interviewer will ask you a number of questions about the health of the members of your family, particularly about the illness and injuries you have had in recent weeks. Your cooperation in helping complete a questionnaire will be very much appreciated. The information you give will of course be held in confidence, We have the assurance of the Public Health Service that the informa- tion will be seen only by authorized personnel of the two agencies and that nothing will be published except statistical summaries in which no individuals can be identified. Sincerely yours, Robert W. Burgess Director Bureau of the Census TI0o653820

is a~ked e:,mcfly as pP~ cn ~ quez~or~e. Required ~fo~m~cnfor ~ch ~er~on ~ ~e responsible ~rEon 18 y~rs o~ age or older and a~ ~me at ~e ~me of~e ~; c~e~e bTa relat~ ~er~n who is r~arded as q~fied to We accu- rate i~oma~on. ~s ~efi~fion ~ an eli~le ~on~ is s~Hed ou~ ~ some detail in ~= ~ter- viewers' h~u~. ~ summa~, a~wers for ~en are Wen by a related ad~t; for a miss~g adult, by wife, parent, or ad~t son or daughter; or for an ad~t not related to ~= head of th~ house- hold, o~y by himself or a =elated ad~. Early ex- perience indicates that for persons over 18 years of age, 58 F~rcent are "self-respondents," w~le ~e remainder for whom another p~rson was informant are designated "pro~-respondents". ~e inte~iew averages ~ minutes. Immediately follovdngthe in~e~iewa "Tha~ You" letter si~ed by the S~geon Gener~ of ~e P~lic Health Se~- ice is hand~ to ~e respondent (fig. 2). In order to minimize ~avel ~me, wor~cads are so arranged that when an inte~ewer is in a neighboxh~ for an inte~ewing assi~ment, he carries ou~ necessa~ list~g operations for seg- ments which are in ~at same neigh~rho~ and w~ch will appear in samples,for ~e next 2 ~len- ~r quarters. Ap~n~x VI sets for~ in some rail ~e manner In which assi~en~s are random- ized over each quarter so that ~ch week's inter- ~ewing constitutes a random sample of th~ popu- lation, and within r~sonable arrangements of workload is widely diversifi~ by ge~raphy and inte~iewer. ~e following statistics for the first 6 months of operation shed added li~t on selected aspects of the collection pr~ess. ~ aH addresses initially schedu1~ for inclusion in ~e sample, 14 percent had ~come, by tim~ of ~II, wha~ are desi~at~ as ~pe B or T~ C exclusions, which are t~es of addresses which should no~ be Inte~iewed: dwelling u~ts which are demolished or which on more caref~ inspection were found to ~ outside chosen sample se~ents; households w~ch were deleted in ~e field, according ~o instructions, through s~sampling o~rations (derails on step are set for~ later in ~e report); households which were vacant; or households whose me~rs had residence elsewhere. ~ those households in which an ~te~iew shoed ~ve ~en conductS, 6 percent were no~nte~iews. ~e perc~t were re- fusals, and five percent were not inte~iewed ~- cause of all other reasons, but princi~lly ~use no one was at home after re~at~ ~Ii ~cks. In a~ut 63 ~rcen~ of households, inte~iew- ing was completed on the first visit. PerCent of households for which varies n~s of revisits proved to ~ necessary are sho~ ~ ~e following breakdown. ~u:zb=~r of visits Percent of all h~rJ~eholds All cases I 63 2 24 3 9 4 3 5 or ~ore i Editing and Processing. The interview is recorded initially in the book questionnaire, Form NHS-1. This form is reviewed for completeness and proper identification of per- son and household, hut other~vise not edited by the supervisor in the Census Regional Office. Reports are batched and transmitted to the Census Bureau in Washington for editing and fumher processing. In Washington, certain control operations are performed, reported information is ceded with special attention being given to medical coding, and to adequacy of data for medical coding (editing reports on inadequate information are returned to Regional Offices for future use in training and in- terviewer control), and the data are transcribed to document-sensed cards and then to punch cards. These cards are processed on conventional punch- card equipment mainly for purposes of interviewer control and for a more thorough check for com- pleteness of entries. Rejects are returned to clerks for review and correction. Corrections and addi- tions are punched and added to the deck. Informa- tion on cards is then transferred to magnetic tape, and further processing is handled on Univac elec- tronic computers. The computer carries out 4 basic opera- tions: (I) an edit of the raw reports; (2) the gener- ation of data from edited reports (e. g., bycounting number of chronic conditions reported for a per- son, to generate the statistic "number of chronic conditions reported for a person"); ~(3) estimation of specified statistics, including all necessary computational steps such as insertion of sampling rates and adjustment for noninterview; and (&) ar- rangement of estimates into derived statistical tables. As for any job of processing and editing re- turns in a sizeable survey, a myriad of steps is necessary. Most of these need no mention in this account. A few circumstances are worth noting. Information moves through 4 separate' chart- nels in processing, each channel being identified as a card, and each card containing the class of information indicated by its title. The four chan- nels are household cards, person cards, condition cards, and hospital cards. In nearly all surveys the choice of definitions and of categorizing devices is critical to the un- T106653821