Eric Walker added Observational study - Wikipedia to Observational studies

Eric Walker added How Covid Sends Some Bodies to War With Themselves - The New York Times to a number of topics

Eric Walker added Observational study - Wikipedia and How Covid Sends Some Bodies to War With Themselves - The New York Times to Observational studies, and added Observational studies to Scientific methodology

Eric Walker added a number of topics and a number of links to Scientific methodology, and added Scientific methodology to Scientific practice