Telephone and Mail Surveys: Advantages and Disadvantages of Each
Dan Zahs and Reg Baker
Market Strategies, Inc.
May 29, 2007
Selecting the mode of administration for a survey requires that one evaluate a number of
factors and understand clearly the tradeoffs involved in choosing one mode over another.
While telephone and mail research share some similar qualities, there are major
differences. We group these differences into four main categories: (1) sample frame; (2)
non-response bias; (3) measurement error; and (4) time and money.
The Sample Frame
A sample frame is essentially a list used to select the sample of persons to be interviewed.
A high quality frame is one that contains a complete or nearly complete list of the target
population. If the frame is sufficiently complete and accurate, a random sample selected
from this frame will be non-biased and representative of the target population.
One major reason for the adoption of telephone as the gold standard for much of
commercial research over the last 25 years has been the quality of the sample frame. The
standard frame for RDD telephone surveys uses information from the telephone
companies about the assignment status of groups of telephone numbers (known as groups
and blocks). Until recently, this frame was considered largely complete and accurate,
with a relatively small number of missing non-telephone households. More recently, the
widespread adoption of cell phones has threatened the integrity of the RDD frame. For
various reasons, cell phones are not part of this standard frame. Until recently, most
people with a cell phone also had a traditional telephone or landline. However, the
proportion households having a cell phone but no landline has been growing rapidly and
is now around 13 percent (Blumberg and Luke (2007)). Using the standard RDD frame,
these cell-only households have no chance of being selected into any sample. When cases
are excluded from the possibility of being selected, bias might be