System dynamics tools are used extensively to assist in understanding complex feedback systems and design high leverage policies. These tools, both qualitative and quantitative, claim to enhance our mental models by enabling us to understand the elements of dynamic complexity, thereby improving performance in dynamic decision-making tasks. However to date these claims have not been subject to rigorous experimental testing. Furthermore, the relationship between qualitative and quantitative system dynamics with respect to their application and their respective usefulness in dynamic decision making tasks has been somewhat controversial The main purpose of this study is to experimentally evaluate the relative efficacy of qualitative system dynamics, quantitative system dynamics and a combination of the two in understanding complex dynamic systems. The results demonstrate if, how and when these methodologies influence our understanding of dynamic situations. Our findings suggest that mere qualitative system dynamics tools are helpful only in tackling simple situations. However, mere quantitative system dynamics tools aid in much more complex problems. Furthermore, the combination of the two tools is aid in the understanding and subsequent performance in tasks involving dynamic complexity.