Validating a novel measure of scientists' disciplinary affiliation that captures its complexity and plasticity.

Much research since the 1950s has investigated scientists' views and behaviors. Employing data from standardized surveys, researchers often analyze how such views and behaviors vary across scientific disciplines. The results of these efforts are likely influenced by the quality of the survey instrument(s) used to measure scientists' discipline or "disciplinary affiliation" as well as the size and quality of respondent samples. Even though disciplinary affiliation is a complex, multi-dimensional construct, most surveys over the years include only a single nominal indicator of one dimension (e.g., the discipline of respondents' highest degree, current department, or self-identity). Only using a nominal indicator-with respondents placing themselves into distinct disciplines assumed to be internally homogeneous-limits our ability to measure variation in their disciplinary affiliation within nominal disciplines. We refer to this variation, or plasticity, in scientists' disciplinary affiliation as disciplinarity, or the extent to which their affiliation may vary along a continuum between strong connection to their discipline's core to broader association with their discipline's frontier-possibly leading to boundary transgression and eventual affiliation with a different nominal discipline. We created a multi-dimensional continuous measure of disciplinarity for use in tandem with a categorical disciplinary affiliation indicator (i.e., discipline of PhD degree) to capture this variation. We included both measures in a standardized survey on scientists' views about the nature of science and experiences in cross-disciplinary research that we administered to a large sample of 4,113 tenure-system science faculty at 83 US research universities. After offering narrative evidence of the content validity of our novel five-dimension disciplinarity instrument, we provide statistical evidence that our resulting disciplinarity scale has construct, convergent, and concurrent criterion validity for measuring the complexity and plasticity of scientists' disciplinary affiliation. We close with suggestions for how other researchers may employ this novel instrument for their own purposes.