2008-2009 ANES Panel Study: error in age summary variable der02, with likely effects on weights

The following error has been identified in the 2008-2009 ANES Panel Study data.

The variable der02, which indicates the respondent's age as of election day in 2008, contains erroneous age data for approximately 3 percent of cases. There are two problems with the variable:

1. There is a spike in the distribution of birth years at 1919, possibly due to data entry errors by respondents trying to type the first two digits of their birth year ("19") in a two-digit year field. This anomaly affects about 30 cases.

2. There is a computation error in the program code used to calculate der02 that affects about 70 cases.

ANES will re-calculate the der02 age variable.

This age variable was used as part of the calculation of poststratified weights. After correcting der02, ANES will re-calculate the weights. The proportion of cases whose age will differ will be small, so the difference between the original weights and the re-calculated weights may also be small.

ANES will release an updated data file with the corrected der02 variable and re-calculated weights.