I have a question about identifying overlap between two lists of regions (each region has a start and end position). I have no experience using ACCESS or any programming, so any advice would be much appreciated. The regions I'm comparing are located on chromosomes (genomic regions), so for each region, there is an Id, a Chromosome number, a start position, and an end position.

For the output, I want to identify all regions in list 2 that overlap each of the regions in list 1. The overlap doesn't have to be 100%; any and all overlap should be identified.

Any help??

Thanks in advance.

Put both tables in the query design with no joins.
Add all the fields from both tables to the design grid.

In the criteria section put the right side of the following under the field named on the left.
First Row:
List2.Start Position: <List1.StartPosition
List2.End Position : >List1.StartPosition

Second Row:
List2.Start Position: <List1.EndPosition
List2.End Position: >List1.EndPosition

The query will take a long time as every record in each table will be compared.