Assertion: experiment | /r/HasProperty | difficult
Facets:
Source sentences:
text: An observational study is used when an experiment would be difficult, unethical, or expensive.
text: It is possible to test more than one, but such experiments and their statistical analysis tend to be cumbersome and difficult.
text: It is possible to test more than one, but such experiments and their statistical analysis tend to be cumbersome and difficult.