Representing experimental variables with EFO
The Experimental Factor Ontology (EFO) provides a systematic description of many experimental variables available in EBI databases, and for external projects such as the NHGRI GWAS catalog. It combines parts of several biological ontologies, such as UBERON anatomy, ChEBI chemical compounds, and Cell Ontology. The scope of EFO is to support the annotation, analysis and visualization of data handled by many groups at the EBI and as the core ontology for Open Targets. We also add terms for external users when requested. If you are new to ontologies, there is a short introduction on the subject available and a blog post by James Malone on what ontologies are for.