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Sampling Bias

Sampling Bias. Sampling is the process of selecting a number of individuals for a study in such a way that the individuals represent the larger group from which they were selected. The purpose of sampling is to gain information about a larger population. Avoiding Sampling Error and Bias.

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Sampling Bias

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  1. Sampling Bias

  2. Sampling is the process of selecting a number of individuals for a study in such a way that the individuals represent the larger group from which they were selected. • The purpose of sampling is to gain information about a larger population.

  3. Avoiding Sampling Error and Bias • Sampling error is beyond the control of the researcher. • It is a reality of random sampling. • If the population is well selected and sufficiently large, chances are the sample will closely represent the population.

  4. Sampling Bias • Does not result from random differences between samples and populations. • It is not random and usually the fault of the researcher.

  5. Examples of Sampling Bias • Study is designed to determines all college students attitudes on drinking. • Researcher polls students outside a bar. All college students are not represented in this sample.

  6. Example of bias • A researcher gets only 45 percent of the surveys she sent out returned. The large number of non-returns represents sampling bias.

  7. If it is not possible to avoid sampling bias, the researcher must decide whether the bias is so severe that the results of the study will be seriously affected. • If the decision is to continue, the bias should be reported in the final research report.

  8. Strategies for Reducing Bias in Qualitative Research Studies.

  9. Extend the study. Stay in the field for a longer time period. Obtain additional data that can be compared to earlier data or to compare participant’s consistency of responses.

  10. Include additional participants to broaden the representativeness of the study and the database.

  11. Make a concerted effort to obtain participant trust, thus providing more detailed honest information from participants.

  12. Work with another researcher and independently gather and compare data collected from subgroups and participants.

  13. Allow participants to review and critique field notes or tape recordings for accuracy and meaning, but only at the end of the entire data collection period.

  14. Use verbatim accounts of observations or interviews by collecting and recording data with tape recordings and detailed field notes, including quotes.

  15. Record in a journal one’s own reflections, concerns, and uncertainties during the study and refer to them when examining the data collected.

  16. Examine unusual or contradictory results for explanations.

  17. Use different data sources to confirm one another.

  18. Descriptive Research Reducing Observation Bias

  19. Observation bias refers to invalid observations that result from the observer’s perceptions, beliefs, and biases, rather than from what is objectively observed.

  20. Observers effect occurs when the presence of the observer makes the persons being observed behave atypically because they are being observed. The best way to handle the problem is to make observers aware of it so that they can attempt to be as unobtrusive as possible.

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