Back Checks

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Back-checks are a quality control method implemented to verify the quality and legitimacy of data collected during a survey. Throughout the course of fieldwork, a back-check team returns to a randomly-selected subset of households for which data has been collected. The back-check team re-interviews these respondents with a short subset of survey questions, otherwise known as a back-check survey. Back-checks are used to verify the quality and legitimacy of key data collected in the actual survey. This page will provide points on how to coordinate, sample for, and design questionnaires for back-checks.

Read First

  • Back-checks are an important tool to detect fraud (i.e. enumerators sitting under a tree and filling out questionnaires themselves).
  • Back-checks help researchers to assess the accuracy and quality of the data collected.
  • Back-checks can be conducted by in-person visits or phone calls. A complementary approach to in-person back checks is conducting Random Audio Audits.
  • Problems identified through back checks can be remedied by further training enumerators or replacing low-performing or problematic enumerators.

Coordinating Back-Checks

  • The total duration of each back-check survey should be around 10-15 minutes.
  • The back-checks should be conducted by a team of specialized back-check enumerators. The back-check enumerators should be experienced, skilled enumerators.
  • The back-check team should be independent from the rest of the survey staff. They should be trained separately and have minimal contact with the survey team.
  • Administer 20% of back-checks within the first two weeks of fieldwork. This helps the research team to identify early whether the questionnaire is effective, whether enumerators are doing their jobs well, and which changes to make to ensure high quality data collection.

Sampling for Back-Checks

  • Aim to back-check 10-20% of the total observations.
  • The back-check sample should be stratified across survey teams/enumerators. Every team and every enumerator must be back-checked as soon as possible and regularly.
  • Include missing respondents in the back-check sample to verify that enumerators are not biasing your sample by not tracking hard-to-find respondents. Also include observations flagged in other quality tests like high frequency checks and observations collected by enumerators suspected of cheating.

Designing the Back-Check Survey

Back-check questions are drawn from the original questionnaire. Innovation for Poverty Action identifies four types of questions that should be included in a back-check to best gauge data and enumerator quality:

  • Questions to identify respondent and interview information:
These questions verify the identity of the respondent and check if, when, and where the original survey took place.
  • Type 1 Variable Questions:
These questions ask straightforward information with no expected variation or room for error. They may include questions about education level, marital status, occupation, whether the respondent has children or not, etc. If Type 1 variable values differ between the questionnaire and the backcheck survey, they indicate poor quality data, a serious enumerator problem, and potentially falsified work.
  • Type 2 Variable Questions:
These are questions for which capable enumerators should get the true answer. If the Type 2 response value differ between the questionnaire and the backcheck survey, they indicate that the enumerator may need more training.
  • Type 3 Variable Questions:
These questions are expected to be difficult. They help research teams to understand if the questionnaire is effectively designed and if enumerators are interpreting difficult and/or nuanced questions correctly and uniformly. If Type 3 variable values differ between the questionnaire and the backcheck, they indicate the need for further enumerator training or, in particular cases, questionnaire modification.

Back-check surveys may also test for translation issues by including questions that could be interpreted differently by different surveyors. Finally, to test whether enumerators are falsifying data to shorten interviews, back-check questions that determine repeated sections of the questionnaire. For example, if there is a long series of questions about household members, verify the correct number of household members. If an agricultural survey asks for production information by plot, verify the number of plots.

Note that it is important that enumerators do not know what questions will be audited. To that end, you may consider randomly changing the back-check survey regularly during data collection.

Analyzing Back-Check Data

After completing a back-check, you can compare the back-check data to the original survey data. This can be done by using the Stata command bcstats, developed by Innovations for Poverty Action. This command produces a dataset of the comparisons between the back-check and original survey data. The command also completes enumerator checks and stability checks for variables.

The steps are as follows:

ssc install bcstats 
bcstats, surveydata(filename) bcdata(filename) id(varlist) [options]

To learn about the options for bcstats and back-checks, please type help bcstats on Stata after installing the command.

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This article is part of the topic Field Management.

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