Good article on assessing data quality of volunteered contributions from citizen scientist:
Christopher Nagy, Kyle Bardwell, Robert F. Rockwell, Rod Christie and Mark Weckel. 2012. Validation of a Citizen Science-Based Model of Site Occupancy for Eastern Screech Owls with Systematic Data in Suburban New York and Connecticut. Northeastern Naturalist 19(sp6):143-158.
We characterized the landscape-level habitat use of Megascops asio (Eastern Screech Owl) in a suburban/urban region of New York and Connecticut using citizen-science methodologies and GIS-based land-use information. Volunteers sampled their properties using call-playback surveys in the summers of 2009 and 2010. We modeled detection and occupancy as functions of distance to forest and two coarse measures of development. AICc-supported models were validated with an independent dataset collected by trained professionals. Validated models indicated a negative association between occupancy and percent forest cover or, similarly, a positive association with percent impervious cover. When compared against the systematic dataset, models that used forest cover as a predictor had the highest accuracy (kappa = 0.73 ± 0.18) in predicting the occupancy observations in the systematic survey. After accounting for detection, both datasets support similar owl-habitat patterns of predicting occupancy in developed areas compared to highly rural. While there is likely a minimum amount of forest cover and/or maximum level of urbanization that Screech Owls can tolerate, such limits appear to be beyond the ranges sampled in this study. Future research that seeks to determine this development limit should focus on very urbanized areas. The high accuracy of the citizen-science models in predicting the systematic dataset indicates that volunteer-based efforts can provide reliable data for wildlife studies.