This thesis compares two methods for studying the problem-solving processes of mechanical design engineers. The first method, verbal protocol analysis, was applied by L. Stauffer to construct a problem-solving model of mechanical design. The second method, timing analysis, measures the time intervals separating drawing or speaking actions during the design process. Timing analyisis was applied by the author to the verbal/video design data collected by Stauffer. This thesis demonstrates that the two methods are statistically related, and hence, that employing two different study techniques enhances the reliability of both methods. The two methods have complementary strengths: protocol analysis reveals the content of the design process, while timing analysis is much more complete. Hence, a combination of protocol and timing analysis provides a stronger measure of the design process than either method alone. / Graduation date: 1992