The purpose of this paper is to review current literature that measures agreement between patient self-report data and a reference standard and to analyze the similarities and disparities between the results of these studies. Patient self-report and reference standard data sources each have strengths and limitations, however, the lack of completeness in often found in reference data sets makes it challenging to measure the true level of agreement between these sources. Based on our research, however, it is clear that patient self-report data is at times more accurate than reference standard data and can serve as an effective means of augmenting reference standard when collected and captured effectively.