ANES time-series studies 1948-1992 were released without respondent-level weights to adjust for nonresponse or within-household selection. Beginning in 1994, however, weights which provide these adjustments in combination with a post-stratification adjustment (constructed to match sample proportions to Current Population Study [CPS] estimates of the distribution of age group by education level) have been included in ANES time-series releases.
Tables in the Guide to Public Opinion and Electoral Behavior were produced from the selection of time-series data available in the ANES Cumulative Data File. Guide tables include unweighted 1948-1992 data but weighted data from studies 1994 and later, using the combination weight present for the latter years. Such a weighting procedure was followed in order to provide the best available estimates for each time point.In addition, it should be noted that, for pre-post studies after 1994, variables VCF0009a, VCF0010a, and VCF0011a represent weighting for the the pre-election wave. Corresponding post-election weights are not found in the ANES Cumulative Data File: it has been assumed that the slight modification in weighting between Pre and Post is small enough to justify simplifying the set of weights included.
Three weights from the ANES Cumulative Data file (VCF0009a, VCF0010a, VCF0011a) are available for production of Guide tables. These 3 weight variables are identical for all years except 1970, each providing no weighting for years prior to 1994 (except 1970) but including the values of the composite weight from years 1994 and later. For 1970, these 3 variables correspond to weights present in the 1970 time-series study.
The 1970 study released 3 variable-level weights, applicable to 3 'types' of 1970 questions (type 0/ type 1/ type 2), where each 'type' of question was administered to a specific selection of respondents:
- VCF0009a applies when a Cumulative Data File variable includes 1970 data from a 1970 type '0' variable.
- VCF0010a applies when a Cumulative Data File variable includes 1970 data from a 1970 type '1' variable.
- VCF0011a applies when a Cumulative Data File variable includes 1970 data from a 1970 type '2' variable.
Note: for those who wish to use ANES Cumulative Data File data without the weighting implemented in the Guide for years 1994 and later, variables VCF0009/VCF0010/ VCF0011 may be used. These provide selection for 1970 weighting without the additional weighting adjustments available after 1992.