This paper reports the results of a comparison of quantitative and qualitative approaches to systems analysis. The primary goal of the investigation was to test a heuristic for qualitative analysis previously proposed by the author that is intended to improve recognition of potential sources of failure for models used for forecasting. A series of papers published by John Sterman, George Richardson, and Pål Davidsen in the mid- to late-1980s examining resource estimation methods and the petroleum lifecycle were selected for analysis based on their completeness and perceived high quality of the models – both quantitative and qualitative. The quantitative results presented in those papers are compared to published data and some potential sources of deviation are identified. The paper then presents an analysis of the qualitative models contained in the papers, highlighting the differences in the nature of insights available from the qualitative and quantitative analyses and illustrating how this expanded logic for qualitative analysis may contribute to the formulation and bounding process for predictive system dynamic models.