Text and Data Mining valid from 2019-05-17
First Online: 17 May 2019
Compliance with Ethical Standards
: The authors declare they have no conflicts of interest.
: The study does not analyze primary data collected by the authors. All procedures performed by the authors and NCES are in accordance with ethical standards.
: Because the study relies on nationally representative secondary data informed consent is not applicable. The authors followed all protocols and procedures in procuring and accessing the data. See ExternalRef removed.