Who Ya Gonna Call?

We are quickly becoming a cell phone society. A recent Centers for Disease Control and Prevention (CDC) survey reports that the number of U.S. household that use only cell phones has surpassed the number that use only traditional landline phones. According to the report, nearly 20% of U.S. households no longer have a landline phone, and that number is rapidly rising. At the current pace, in less than 10 years the majority of U.S. households will not have a landline phone.

What this means to researchers is that traditional telephone sampling methods are becoming less representative of the general population. In fact, Marketing Systems Group, a leader in telephone survey samples recently reported:

“The unfolding changes in US telephony have introduced new sources of undercoverage in traditional RDD samples with magnitudes that are no longer ignorable.”

In addition to RDD samples, listed telephone samples face the same challenges in that there are not yet and are not likely soon to be directories of personal cell phone numbers. Unfortunately, we have gotten to a point where using any traditional telephone sampling methodology subjects a survey to the risk of exclusion bias.

As we move forward, sampling strategy will play an increasingly important role in research design. As reliable sources of telephone samples fade, new sources of online samples are emerging, not only with traditional opt-in panels but in other areas such as within social networks. Many of these communication outlets are popular with the cell phone only set. Combining various sources of survey respondents can often generate a sample that is more representative than any single source alone. While there will never be a way to get a perfectly representative sample, there will always be a way to improve the representativeness, and a good researcher should be able to advise you how.

The CDC report also highlights important demographic differences between the growing breed of cell phone only households and those with traditional landline service – differences that researchers must address.

Who has gone wireless?

• 39% of renters
• 10% of those who own their home
• 33% aged 18-24
• 3% aged 65 and older
• 21% who are living in the South
• 17% who are living in the West
• 20% of men
• 17% of women