"Calibration" is an aspect of metacognition that describes how well students assess their own knowledge. One tool that can help to assess student calibration is the knowledge survey (KS). On a KS, students rate their confidence in their ability to answer questions related to course content. A comparison of a student's confidence level with their actual performance on course exams gives an indication of the student's metacognitive calibration. We report on a study that explores students' responses to a KS in introductory physics and chemistry courses serving both STEM and non-STEM populations. In many courses, Delta (the difference between KS-score and final exam score, a measure of calibration) was anti-correlated with final exam performance. No relationship was found between Delta and students' scientific reasoning abilities. We also report preliminary findings on how calibration differs for questions of a quantitative nature vs. those of a more conceptual nature.