We describe the application of the Evidence-Centered Design (ECD) framework to measure the self-regulated learning (SRL) strategies of students' enrolled in an online mathematics course by using their trace logs captured by a Learning Management System (LMS). We found that the ECD framework was helpful in building evidentiary arguments for measuring SRL, particularly in connecting theoretical constructs and student activities in the LMS. We used the framework to explore differences between successful and unsuccessful students' use of SRL strategies over the course of the semester. A logistic regression model only resulted in one significant variable, the total number of logins. However, time series plots revealed considerable temporal differences in how students used SRL strategies, with successful students showing more consistent application.