The main advantage of using the telephone interview as a market research technique is the relatively low cost involved. While it is a less reliable method of research than the personal interview, it is nevertheless very simple and quick to perform. Given an efficient telephone service and a quiet office away from outside disturbances, it is possible to conduct between five and six brief interviews per hour. Of course, you will need to have a list of companies to call (and probably the target person's name). Nevertheless, a good directory should be able to provide this information for you and you may be able to get the directory from the local chamber of commerce.

Telephone interviews are often the best way to conduct a survey among busy executives or others who would not be willing to grant the time for a personal interview and the response rate is much higher than that obtained from postal surveys. Of course, the biggest problem with telephone interviews is the issue of language. You will probably only be able to turn to telephone interviews in English-speaking countries and even then, accents and colloquialisms can make an interview very difficult.

The main applications of the telephone interview are:

• Selecting subjects for personal interviews by identifying respondents' main areas of interest and suitability for a survey
• Obtaining simple statistical information such as the number of brands carried in a particular product line, or the available number of retail outlets
• Checking or confirming information received in personal interviews or postal surveys

Other disadvantages of telephone interviewing include the following:

• The questionnaire must be short and simple, thus limiting the depth and range of information gathered
• A steady flow of conversation must be maintained, making it difficult for the respondent to pause and think
• The respondent's attitudes and reactions are difficult to assess
• Confidential information is rarely given over the telephone, again limiting the depth of a telephone survey
• In many field situations, a representative sample of the population might not have a telephone service, thus introducing a bias to the information gained
• If the researcher has a less than perfect knowledge of the language spoken in the market, it will be particularly difficult to gain useful information through telephone interviews

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