i2b2 Ontology and CRC Discussion: 1

Questions asked and points to ponder. Access to the demo database is useful here...

Ontology Cell tables compared to CRC concept_dimension table

There are three ontology tables within the demo Ontology cell: birn, i2b2 and custom_meta.

When I do a select count(*) from <table_name> where c_visualattributes like '%LA%' I get the following figures:

• birn: 37
• custom_meta: 0
• i2b2: 93807

When I do a "select count(*) from concept_dimension" within the CRC cell I get a count of 73590.

The totals are 93844 as opposed to 73590. Why is there a difference and what does it mean?

In an Ontology table, what does c_columndatatype really mean?

The docs state: "either ‘T’ for text or ‘N’ for numeric and describes the datatype of the concept". Yet the length of the column is varchar 50.

Within the demo project:

• select count(*) from i2b2 where c_columndatatype like '%N%' ===> returns 0
• select count(*) from i2b2 where c_columndatatype like '%T%' ===> returns 134762
• select count(*) from i2b2 ===> returns 134762

Yet within the query tool (from the Workbench) I can select terms from a Labtest and constrain by value. This is undoubtedly possible because of the optional metadataxml column. But even so, what does c_columndatatype really mean?