Supervisor-to-Interviewer Ratio

This entry addresses the issue of how the average number of interviewers that are assigned to a survey supervisor affects data quality. There are many factors that affect survey interviewer performance and success. Individual skill set, training, experience, and questionnaire design all influence the ability of interviewers to gain cooperation and gather accurate data. The one ongoing factor that has a significant impact on data quality in surveys that are interviewer-administered is the interaction of the supervisor with the telephone interviewer. Sometimes called a monitor, coach, team lead, or project/section/floor supervisor, this staff position gives management the greatest leverage to influence the human aspect of such survey projects.

The supervisors of survey interviewers may fulfill many roles in a survey project, including any or all of the following:

• Monitor the quality of the data being collected.
• Motivate the interviewers to handle a very difficult job.
• Provide insight into how a study is going and what the problem areas are.
• Provide training to improve the interviewing skills of the interviewers.
• Supply input for the interviewer performance evaluation.

It is the supervisor who is in daily contact with the interviewers and who knows each interviewer's strengths and skills to be developed, maintained, or enhanced. The supervisor answers questions, guides interviewers through new or difficult processes, and sets the mood, pace, and outlook of the whole team. A supervisor who is positive, uplifting, professional, and supportive will increase retention of interviewers, improve data quality, and lower costs of the project. There have been many human resource studies that show employees are most influenced by their immediate supervisor to be happy in their jobs or to leave a job. To ensure the best results on survey projects, research management must not only select the right people to be motivating, inspiring supervisors but also determine the right ratio of interviewer to supervisor.

The right ratio for a project is the one that provides enough supervisory coverage to meet the above goals: retain interviewers, ensure good quality, and provide cost efficiencies. A ratio that is too high (e.g.> 1:20) for a project's needs will lead to too little interaction with interviewers, lower-quality data, and increased turnover. A ratio that is too low (e.g. 1:5 or less) for a project's needs will increase costs and may lower supervisory motivation due to boredom. To meet the challenge of determining the correct ratio for a project, research management can use a checklist of criteria questions.

Some suggested questions to help develop the right ratio include the following:

• 1.
  Is the study a new type of survey in its content, group to be sampled, procedures, or client/industry? If the interviewers are not experienced with the type of study being done, the supervisor-to-interviewer ratio should be lower than the normal benchmark (e.g. < 1:10).
• 2.
  Is the study an ongoing survey that will change very little, or will the questions, procedure, shifts, and sample change frequently? An ongoing study with few changes will need a lower ratio of supervisor to interviewer, but a survey with constantly changing requirements needs proportionally more supervision.
• 3.
  Does the study have very stringent or complex requirements, such as complicated sample quotas, sensitive or difficult selection criteria, or comprehensive validation? If there are other measurements besides real-time monitoring of interviewers' work and answering questions that must be tracked hourly, daily, or frequently within a shift by the supervisors, such as in the case of centralized telephone surveys, then a lower ratio is demanded.
• 4.
  Is the project a business-to-business study, or a social/political study that requires respondents who are professionals or executives, like doctors, lawyers, chief executive officers, and so forth? Interviewers will have to possess more professional skills on these projects and may need more guidance from supervisors on getting through gatekeepers and other obstacles. Surveys conducted with professionals or highly [Page 859]affluent households or households with high-security access challenges often require a lower ratio than general consumer surveys.
• 5.
  Does an ongoing project typically have a high percentage of new or inexperienced interviewers? If a survey organization experiences a steady, high level of turnover and an influx of raw interviewers, the supervisor-to-interviewer ratio will need to be lower to support the development of this staff.
• 6.
  Is the study or project one that is audited by an independent group, or is there a third party that has oversight on the survey procedures and requirements, such as a government agency or industry watchdog committee? The project may need proportionally more supervisors to ensure compliance with the audit or oversight.
• 7.
  Does the client funding the project represent a major portion of the survey organization's business or is otherwise a high-profile client with heavy impact on the organization's success? If so, then management may allocate more supervision to make sure all aspects of the work are going well and according to client expectations.
• 8.
  What is the budget for the project? How was the bid costed out when the work was contracted? How much supervisory costs were built in? The manager may be restricted in what he or she can work with on the ratio by the cost expectations already set up by the company or the client.

Once all of these questions have been answered, the project management can derive the supervisory ratio best suited for that project. There has to be a beginning point, or benchmark, that the manager uses to develop the specific ratio. Although there is no one benchmark used by all survey research data collection centers, a common range of ratios for supervisor to interviewer in many commercial organizations that do interviewing is in the range of 1:15 to 1:20 of supervisor per interviewers. Starting with that range, the manager can work up or down in setting the ratio against the sample questions listed previously. In contrast, since the 1980s, Paul J. Lavrakas has advised that for high-quality supervision, this ratio for supervising telephone interviews should be more in the 1:8 to 1:10 range.

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