Data Extraction Errors Research Articles

Systematic review data extraction: cross-sectional study showed that experience did not increase accuracy

Objective This study assessed the impact of systematic review and data extraction experience on the accuracy and efficiency of data extraction in systematic reviews. Study Design and Setting We conducted a prospective cross-sectional study from October to December 2006. Participants were classified as having minimal, moderate, or substantial experience in systematic reviews and data extraction. Three studies on insomnia treatment were extracted. Our primary outcome was the accuracy of data extraction. Data sets of each experience level were analyzed for errors in data extraction and results of meta-analyses. Additionally, the time required for completion of data extraction was compared. Results Error rates were similar across the various levels of experience and ranged from 28.3% to 31.2%. Mean rates for errors of omission (11.3–16.4%) were generally lower than those for errors of inaccuracy (13.9–17.9%). There were no significant differences in error rates or accuracy of meta-analysis results between groups. Time required approached significance, with minimally experienced participants requiring the most time. Conclusion Overall, there were high error rates by participants at all experience levels; however, time required for extraction tended to decrease with experience. These results illustrate the need to develop strategies aimed at mastery of data extraction, rather than reliance on previous data extraction experience alone.

Disagreements in meta-analyses using outcomes measured on continuous or rating scales: observer agreement study

Objective To study the inter-observer variation related to extraction of continuous and numerical rating scale data from trial reports for use in meta-analyses.Design Observer agreement study.Data sources A random sample...

Channel change on the River Dee meanders, 1946–1992, from the analysis of air photographs

Gurnell et al. (1994) identified spatial and temporal trends in the planform of the River Dee on the Welsh–English border over a 115 year period (1887–1992) by overlaying information primarily derived from historical maps within a GIS. This paper focuses on channel change within the same river reach over the last 50 years based on the analysis of information from six sets of air photographs within a GIS. The shorter time period of study has resulted in greater difficulty in identifying channel changes which exceed the errors incurred in information extraction from the photographs and registration to a common map base. However, consistency in the spatial and temporal trends identified from different sources and for different stretches within the study reach support interpretation of channel change. Air photographs contain more information that is relevant to the interpretation of processes of channel change than can be obtained from maps. For example, information on bank cover and the pattern of sediment deposition are explored. However, information obtained from air photographs requires careful handling if errors in data extraction and registration are to be minimized. The analysis of channel planform information from air photographs presented in this paper confirms some of the tentative conclusions previously drawn from the analysis of information derived from maps of the same river stretch. Additional information on downstream changes in the spatial extent and pattern of sediment deposition and on temporal trends in bank vegetation cover, that has been extracted from air photographs, provides further details of possible adjustments to flow regulation, indicates the importance of vegetation cover to bank sedimentation processes and illustrates a downstream change in the mode and distribution of sedimentation across the fluvial–tidal transition. © 1997 by John Wiley & Sons, Ltd.