question on how to handle values below MDL
Randy Carver
First the background: I've been working on a custom web app (WILBuR) that uses ODM and will publish WaterOneFlow compliant webservices (soon!), its being used by Grand County Water Information Network (GCWIN), a non-profit here on the upper CO River Basin. Due to budget constraints, a full MS Stack was not an option, so WILBuR is written on a LAMP Stack. GCWIN has over 3 million data points in the db at this point, with the data accessible to the local public via the web app and downloadable data as per the non-profits mission. Most of the currently loaded data is continuous water temp and related data, with some secchi data.
My question has to do with how people are handling data below MDL. We're getting ready to load Algae Toxin data in and we have some data values that come back as <MDL from the lab. This is not a case of No Data Value, so I don't think using the NDV value assigned in the variable is correct. Are there any Best Practices to follow when loading data with some values below MDL? Any recommendations?
Thanks in Advance!
Kim Schreuders
Randy,
This situation is exactly what the CensorCodes are for. You make sure that a code such as “<MDL” is included in the CensorCodeCV, and then “<MDL” for the CensorCode in each relavant DataValues record. You can then put either a NoData value in the Value field, or you can put the MDL value in the value field. If you put the MDL value in the value field, you might just want to use “<” for the CensorCode.
For more info, search for CensorCode in the CUAHSI Community Observations Data Mode (ODM) 1.1 Design Specification (http://his.cuahsi.org/documents/ODM1.1DesignSpecifications.pdf).
Kim Schreuders
CUAHSI HIS Team
Kim Schreuders
Randy,
Just a minor correction to my previous message. It seems that the term: ‘lt’ with the definition: ‘less than’ is already in the CensorCodeCV. So that leads to to think that when loading the DataValues table, it would be best to use ‘lt’ for the CensorCode, and the MDL value as the Value, since that is most consistant with the existing controlled vocabularies.
Kim Schreuders
CUAHSI HIS Team