CUMULATIVE DATA FILE - GENERAL INTRODUCTION

     The Cumulative Data File consists of variables derived from the 1948-2004
series of biennial ("time-series") SRC/CPS National Election Studies.
[NOTE:  No ANES study was conducted in 1950; 1954 was a minor study although
its data are included here.]

     To produce this dataset, cross-section cases from the time-series
election studies have been pooled; the total unweighted cross-section N is
46,226.  (NOTE:  non-cross-section cases from black supplements in 1964, 
1968 and 1970 are not included in this file.) 

     A variable in the dataset almost always represents a question which
has been asked in three or more (time-series) studies.  This dataset
incorporates for specific questions data from all time-series studies in
which the question was asked in comparable fashion.

     When using variables from this dataset, the analyst should keep the 
following in mind:  
  1) Question wording has varied over the years.  Where there are 
     differences in question wording, we have tried to reference them 
     in the documentation; completeness of this effort, however, cannot
     be guaranteed. 
  2) Even if a question is worded identically in successive surveys, its
     placement in the survey instrument may be different, with unknown (and
     possibly large) effect. 
  3) Variables have been recoded to be consistent over time. Questions are not
     necessarily coded the same way in this dataset as they are in the
     election study datasets from which they came.



               THE SAMPLE SIZES FOR ALL YEARS ARE AS FOLLOWS:         

                              Cross-section *
                           Weighted**  Unweighted  
                           
               1948:            --        N=662
               1952:            --        N=1899  
               1954:            --        N=1139  
               1956:            --        N=1762  
               1958:          N=1822      N=1450  
               1960:          N=1954      N=1181
               1962:            --        N=1297
               1964:            --        N=1571  
               1966:            --        N=1291 
               1968:            --        N=1557 
     type 0*   1970:            --        N=1507 
     type 1*   1970:          N=835       N=758
     type 2*   1970:          N=817       N=749
               1972:            --        N=2705 
               1974:          N=2523      N=1575 
               1976:          N=2869.5    N=2248   
               1978:            --        N=2304  
               1980:            --        N=1614
               1982:            --        N=1418
               1984:            --        N=2257
               1986:            --        N=2176
               1988:            --        N=2040
               1990:            --        N=1980 ***
               1992:          N=2488      N=2485
               1994:            ****      N=1795 
               1996:            ****      N=1714 
               1998:          N=1281      N=1281
               2000:          N=1807      N=1807
               2002:          N=1511      N=1511
               2004:          N=1212      N=1212


*  note: the 1970 figures exclude 73 non-eligible Rs in the original dataset's
   cross-section N.  The Cumulative File excludes all non-eligible respondents 
   from its cross-section.  For descriptions of type 0, type 1, and type 2
   variables in 1970, see weight vars VCF0009-VCF0011.
** note: the weighted cross-section Ns are represented in the Guide to Public
   Opinion and Electoral Behavior, which was produced using data from the
   Cumulative File.  To reproduce the data appearing in the Sourcebook, it is
   necessary to use appropriate weights (see VCF0009-VCF0011).         
***note: 20 cases have been deleted from the 1990 Study data due to belated
   discovery of interview fabrication and ineligible Rs.
****note: In 1992 and later studies there were multiple weights which can be 
   used with the data; see Study documentation.