List-assisted random digit dialing (RDD) is the sampling procedure that is normally used in constructing samples of telephone households. This is a truncated design because it only includes telephone hundreds banks with one or more listed numbers. However, this design has become widely accepted after a 1995 study found that only 3.7% of working household telephone numbers fell in the unlisted banks with no significant demographic biases.

A recent study has re-examined the coverage of 100-series banks with one or more listed telephone numbers for landline households. Fahimi and his colleagues concluded that “the coverage loss for designs based on the 1+ listed banks is closer to 20% than 4%” today. Such a coverage error would call into question the acceptability of the current RDD sampling procedures for landline households, and in combination with cell phone coverage issues, the very future of telephone surveys.

The current study attempts to replicate the Fahimi study with sample from a second vendor and a somewhat different process for classifying households and non-households. Based on a national RDD sample of 10,000 numbers from 1+ listed banks and 27,175 numbers from unlisted banks, we find that 95% of landline households are still located in 1+ listed banks. These findings would seem to support the continued viability of list-assisted RDD sampling in the design and conduct of telephone surveys.

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