GENERAL INFORMATION                                
                                                                                
     The NHANES III Examination Data File contains data collected in the        
     mobile examination center (MEC) as well as data collected during the       
     home examination.  The documentation pertaining specifically to the        
     Examination Data File is divided into four main sections.  The first       
     section, "General Information," provides information about the contents    
     of the Examination Data File.  The second section, "Data File Index,"      
     includes a brief description of all the variables on the data set and      
     shows the standard name of each variable and its position in the data      
     set.  The third section, "General Notes, Item Descriptions, Codes,         
     Counts, and Notes" provides for each component, a description, the         
     standard variable name and a brief description of the values               
     that variable can take on, a count of the frequency of occurrence of       
     each value, notes by variable, and appendices as necessary. "References"   
     are provided in the fourth section.                                        
                                                                                
     Components administered in both the MEC and the home (e.g., spirometry,    
     body measurements, physical function evaluation) are combined in this      
     file if data collection methods were comparable.  The file includes        
     information from all the examination components as well as from all the    
     questionnaires administered in the examination center and during the       
     home examination.  In addition, data on total nutrient intakes, food       
     sufficiency, intake of plain drinking water, and salt use are also         
     included as part of this file.  However, detailed information about the    
     individual foods reported by respondents during the dietary interview      
     are contained in a separate NHANES III Dietary Data File.  Data from       
     blood and urine specimens are not contained in this file, but are in a     
     separate NHANES III Laboratory Data File.  Data from two examination       
     components, electrocardiography (ECG) and radiography of the hands and     
     knees, are not included in this file.  ECG data will be released later     
     with comparable data from NHANES I and NHANES II.  The x-ray data will     
     also be released later, after the images have been digitized. See the      
     Table of Contents for a complete list of components included in this       
     NHANES III data release.  Since eligibility for examination components     
     was determined by the age of the examinee, the components of this file     
     are in order according to the target age group for each component, from    
     youngest to oldest.                                                        
                                                                                
     Sample persons were examined in the MEC within four weeks of the           
     household interview.  However, a home examination was scheduled for        
     those aged 2-11 months or 20 years and over who were frail or unable to    
     come to the MEC.  The home examination was designed to gather certain      
     physical and physiological information on sample persons in their own      
     homes through a subset of components normally done in the MEC.  These      
     components were: body measurements, venipuncture, spirometry, cognitive    
     testing, and physical performance testing.  Interviewed persons who        
     completed at least one test or examination at the home were defined as     
     home-examined.                                                             
                                                                                
     Staff recorded all examination data directly into an automated data        
     collection system.  All staff received intensive initial training, and     
     formal retraining programs were conducted throughout the survey to         
     ensure that high skill levels were maintained.  Details on survey          
     instruments and forms, training manuals, and data collection               
     procedures are published elsewhere (U.S. DHHS, 1996b).                     
                                                                               
     Data processing and editing were performed to ensure internal data         
     consistency within components.  Processing procedures are described in     
     each chapter of the this file.  Notes are provided for standardized and    
     recoded variables, and for variables requiring additional information.     
     In some cases exceptions to the NHANES III conventions made in order to    
     enable NHANES III results comparisons with results from earlier surveys    
     or other studies.  Such exceptions are described in the introduction to    
     the affected component or in individual variable notes.                    
                                                                                
     One should note that for components such as the Dental Examination and     
     Audiometry which include negative value responses, value labels that       
     include ranges use a hyphen to indicate a range, from negative to          
     positive.  For example, a range of -10 to 105 is written as -10-105.       
                                                                                
     Since NHANES III is based on a complex, multistage sample design,          
     appropriate sampling weights should be used in analyses to produce         
     national estimates of prevalence and associated variances while            
     accounting for unequal probability of selection of sample persons.         
     The final MEC examination weight, WTPFEX6, should be used for analysis     
     of the questionnaires and measurements administered in the MEC (except     
     for the allergy and central nervous system tests, which were performed     
     on half-samples and have their own weights), as well as for a combined     
     analysis of measurements from the MEC examinations and associated          
     medical history questions from the household interview.  The final         
     MEC+home examination weight, WTPFHX6, should be used only in               
     conjunction with the MEC+home examined sample, and only with items         
     collected in both the MEC and the home.