Completion Rate

The term completion rate has been used often in the survey research literature to describe the extent of cooperation with and participation in a survey. However, it is an ambiguous term because it is not used consistently. Therefore readers of the literature should interpret the term with caution.

Completion rate is often used to describe the portion of a questionnaire that has been completed. In self-administered surveys, it is used widely to differentiate between the number of eligible individuals who do not complete a questionnaire and those who do. In this context, the completion rate is the number of questionnaires completed divided by all eligible and initially cooperating sample members. Researchers using completion rate in this sense should state so explicitly. This rate is an important indicator of item nonresponse in self-administered surveys. It has implications for the visual layout of a self-administered instrument, since the layout may affect how willing sample members are to complete the questionnaire. In addition, it also has implications for the content and the placement of critical questions in the questionnaire.

Completion rate is also an umbrella term used to describe the extent of sample participation in a survey—including the response rate, the contact rate, and the cooperation rate. Since these outcome rates are often used as criteria for evaluating the quality of survey data, analysts and other data users should know which rate is being referred to by the term completion rate. The response rate indicates the proportion of the total eligible sample that participates in the survey, the contact rate indicates the proportion of those contacted out of all eligible sample members, and the cooperation rate indicates the proportion of the contacted sample that participates in (or consents to participate in) the survey. The American Association for Public Opinion Research (AAPOR) recommends that researchers define how they are using the terms response rate, contact[Page 113]rate, and cooperation rate and offers standard definitions for these terms and how they should be calculated. AAPOR recommends that researchers explain in detail how they calculated the rates and how they categorized the disposition codes. Of note, AAPOR does not define the calculation of the term completion rate.

In addition to responding to a survey, people may participate in studies in other ways as well, and instruments other than questionnaires are often used to collect data. For instance, a screener interview may be used to determine an individual's eligibility for a study before he or she is asked to participate in the full survey. In addition to self-reported information collected during an interview, other data may be collected from participants, such as biomeasure data (height and weight measures, hair samples, or saliva samples). In epidemiological or randomized controlled studies, sample members may be asked to participate in a health regimen, in special education programs, or in an employment development program. The term completion rate may therefore be used to indicate the extent to which any or all of these activities have been completed. This more or less “universal” nature of the term underscores the importance of denning how it is being used in any given context. For example, in reporting findings based on biomeasure data, researchers should be clear about whether completion means completing the questionnaire only or if they are referring to completing the additional data collection.

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