Conventional physics laboratory courses generally include an emphasis on increasing students' ability to carry out data analysis according to scientific practice, in particular, those aspects that relate to measurement uncertainty. This study evaluates the efficacy of the conventional approach by analyzing the understanding of measurement of freshmen following the physics major sequence, i.e., top achievers, with regard to data collection, data processing, and data comparison, through pre- and postinstruction tests by using an established instrument. The findings show that the laboratory course improved the performance of the majority of students insofar as the more mechanical aspects of data collection and data processing were concerned. However, only about 20% of the cohort of physics majors exhibited a deeper understanding of measurement uncertainty required for data comparison. (Contains 5 tables, 2 figures, and 31 notes.)