measurement datum evidence quality The quality of an evidence item is a measure of the rigor applied in performing the study and anlysis tasks used to produce it. Higher quality studies will have carefully defined controls, and be replicated numerous times to ensure reproducibility. Other factors that are often used as secondary indicators of the quality of research data include the quality of the journal in which it is published, and the reputation of the lab or institution performing the study. Evidence qualitty is an important factor in assessing the overall strength of evidence it may produce. A data item that indicates the quality of the data used as evidence by an agent making an assertion.