"Rigorous study" refers to a type of learning or research that is thorough, detailed, and demanding. It involves a careful and systematic approach to gather information, analyze it critically, and draw accurate conclusions. Full definition
The recommendations in this guide reflect not only our expertise and experience but the findings of rigorous studies of interventions to promote reading achievement. (ldaustralia.org)
As it turns out, a slew of more rigorous studies have found no scientific basis for such claims. (discovermagazine.com)
To be prepared for rigorous study in school, and for the working world after formal education is completed, students must be able to use language effectively. (ksassessments.org)