Student learning in instructional physics labs represents a growing area of
research that includes investigations of students' beliefs and expectations
about the nature of experimental physics. To directly probe students'
epistemologies about experimental physics and support broader lab
transformation efforts at the University of Colorado Boulder (CU) and
elsewhere, we developed the Colorado Learning Attitudes about Science Survey
for Experimental Physics (E-CLASS). Previous work with this assessment has
included establishing the accuracy and clarity of the instrument through
student interviews and preliminary testing. Several years of data collection at
multiple institutions has resulted in a growing national data set of student
responses. Here, we report on results of the analysis of these data to
investigate the statistical validity and reliability of the E-CLASS as a
measure of students' epistemologies for a broad student population. We find
that the E-CLASS demonstrates an acceptable level of both validity and
reliability on measures of, item and test discrimination, test-retest
reliability, partial-sample reliability, internal consistency, concurrent
validity, and convergent validity. We also examine students' responses using
Principal Component Analysis and find that, as expected, the E-CLASS does not
exhibit strong factors.Comment: 10 pages, 4 figures, 7 tables, submitted to Phys. Rev. ST - PE