What is the main consequence of measurement error?

Measurement error primarily impacts the reliability and validity of data. Reliability refers to the consistency of a measurement—if measurement error is present, the same measurement repeated under the same conditions will not yield the same results, leading to increased variability in data. Validity pertains to how well the measurement actually reflects the concept it aims to quantify; measurement error can lead to inaccurate conclusions about the relationships being studied, thereby reducing validity.

When there is significant measurement error, it becomes difficult to trust the data to truly represent the phenomenon being studied, which can compromise the study's findings and recommendations. Compatibility of results with theoretical predictions, generalizability, and applicability can all be influenced by the extent of this error. Thus, the main consequence of measurement error is indeed a decrease in both reliability and validity of research findings.