Developing a culture of evidence to assess and improve teacher preparation programs is a critical issue in American education. Teacher education has been struggling with the challenge of preparing and retaining sufficient numbers of high-quality teachers who can work effectively with students from all cultural and racial backgrounds, raising the achievement for all students. Many scholars suggest that a strong research base on how best to prepare teachers to meet the challenges of today's classrooms is lacking. This study investigated the effect selected extrinsic variables have on survey data collected to determine the efficacy of, and improve, teacher preparation programs. While recognizing other aspects of program evaluation, isolating the effects of extrinsic variables on the survey results is an important step to determining whether the results can be accepted at face value or if they are influenced by outside factors over which programs have no control. In working toward a culture of evidence concerning teacher preparation, all schools, departments, and colleges of education of the 23 California State University (CSU) campuses established common assessments as recommended by Cochran-Smith (2009) and Darling-Hammond (2006). This study examined two factors specific to the preparation programs, and four extrinsic factors specific to the K-12 schools in which surveyed graduates were teaching. (Contains 3 tables.)