  Proficiency with calculating, reporting, and understanding measurement
uncertainty is a nationally recognized learning outcome for undergraduate
physics lab courses. The Physics Measurement Questionnaire (PMQ) is a
research-based assessment tool that measures such understanding. The PMQ was
designed to characterize student reasoning into point or set paradigms, where
the set paradigm is more aligned with expert reasoning. We analyzed over 500
student open-ended responses collected at the beginning and the end of a
traditional introductory lab course at the University of Colorado Boulder. We
discuss changes in students' understanding over a semester by analyzing
pre-post shifts in student responses regarding data collection, data analysis,
and data comparison.
