Measurement Bias: Nonrandom measurement error; a form of inaccurate measurement in which the data consistently overestimate or underestimate the true value of an event. Applied Behavior Analysis (2nd Edition)
Understanding the Core Concepts:
- Measurement Error: In any data collection process, there will be some degree of difference between the observed value and the true value of what you’re measuring. This difference is measurement error.
- Random Error: This type of error is unpredictable and fluctuates. Sometimes your measurement might be slightly higher than the true value, and sometimes slightly lower. Over many measurements, these errors tend to cancel each other out, and the average measurement will likely be close to the true value.
- Nonrandom Error (Bias): This is a systematic error that consistently pushes your measurements in a particular direction. It doesn’t fluctuate randomly; instead, it consistently overestimates or underestimates the true value. This is what measurement bias is.
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