[Differences between listed and unlisted telephone subscribers among telephone survey respondents]

The number of telephone surveys conducted has increased in Japan, with the telephone directory often used for sampling respondents in telephone surveys. As some subscribers request that their numbers not be listed, they are excluded. The Random Digit Dialing (RDD) survey method, however, not only makes possible smooth data collection, but also random sampling of all subscribers in telephone surveys. The authors conducted a telephone survey in Tokyo using the RDD method to investigate any differences in behavior and demographic or social attributes between listed and unlisted subscribers. These attributes included gender, age, family size, job, and residential area. The findings were as follows: 1) The listing rate in telephone directories was 65.8% among respondents. 2) Old age, large family size and certain residential areas correlated with higher listing rates. 3) Nevertheless, the relationship between listing in the telephone directory and residential area remains somewhat unclear due to the confounding attributes of age and family size. 4) Using Hayashi's second method of quantification, age, family size and occupation correlated with listing frequency. 5) There were also significant differences between listed and unlisted subscribers on questions of health maintenance and lifestyle.