Parts of a Research Study Where Bias Can Occur

• Planning the Study
• Selecting Participants
• Seeking Funding
• Reporting the Results
• Conducting the Study

Note: Bias can be an issue in every stage and part of a research study.

Validity vs. Reliability

• Quality Evidence: Just because a research article sounds professional, uses technical language, is authored by experts, and reports impressive results, it does not necessarily mean it is credible.
  • Example: A 1998 study published in a peer-reviewed journal claimed a link between the MMR vaccine and autism, which was later proven to be critically flawed but had already caused significant mistrust in vaccines.

Which Situation is Not Possible?

• High Reliability and High Validity: Possible
• High Reliability and Low Validity: Possible
• Low Reliability and High Validity: Not Possible
• Low Reliability and Low Validity: Possible

Explanation: To be valid, a measurement or instrument must also be reliable. Therefore, low reliability cannot coexist with high validity.

Types of Validity

• Internal Validity: The study establishes a trustworthy cause-and-effect relationship between a treatment and an outcome.
• External Validity: How the study results are applicable in other settings or the generalizability of the study results.
• Construct Validity: Does the test measure what it is supposed to measure?
• Content Validity: Are the test items fully representative of the entire domain they are intended to measure?
• Conclusion Validity: The conclusions of the study are reasonable.

Types of Reliability

• Concept: Reliability refers to the consistency of measurement. A reliable measure can be replicated.
• Example Issue: In a qualitative study using coding as a method, if two researchers reach different conclusions on the codes applied to interview transcript data, it is an issue of reliability.