# Presentation: 415706

## Missing Value ReasonSmall Group Report to the VCDE WS F2FJune 17, 2005

- Harold Solbrig
- David Aronow
- Rebecca Crowley
- Jim Kadin
- Kim Klingler
- wiki

## Formerly known as Flavors of Null,FoN became Missing Value Reasons

- Changed name as clarified focus of Group
- “Null “ is ambiguous (reserve for status of a cell in a database, when nothing is posted to that cell)
- Realized we are concerned with situations in which a ‘meaningful’ data value is not available
- CDE development efforts often desire to support explanation of why ‘meaningful’ values are not available

## This Report....

- We have achieved some conclusions, which will be presented in this Report
- But fundamental questions remain unresolved – issues we will also raise in this report, for your consideration

## “Meaningful” values v. Missing values

- A working definition of ‘meaningful’ might be that a ‘meaningful’ value ‘answers’ the ‘question’ posed by a data element
- In contrast, a Missing Value Reason ‘answers’ the implicit ‘question’ “Why is there no ‘meaningful’ value, when there is none?”

## MVR Scope

- MVR can apply to all data types – enumerated, date, number, string, etc.
- For non-enumerated CDE, the MVR are recorded in a data field separate from the ‘meaningful’ value
- For enumerated CDE, the MVR can be recorded in either the same data field as, or a separate data field from, the ‘meaningful’ value (details later)

## Vocabulary v. Applications

- 	Missing Value Reasons are defined and used in terms of vocabulary and CDE (the currency of exchange between information systems), not in terms of application or database design or implementation.

## MVR may not only be MVR

- Terms may be MVR in one application context, but not in another context
- Example: Not specified
- In an automated data feed of lab result nominal values such as ‘High’, ‘Low’, etc., the value ‘Not specified’ explains why a ‘meaningful’ value was missing
- For CDE Self Reported Person Sex Text Type, the value ‘Not specified’ means, in part, undifferentiated, which is a ‘meaningful’ answer

## MVR and EVS

- EVS should be robustly stocked with terms that cover a broad range of MVR which can be extended as needed
- CDE curators can select terms from the EVS stock as needed
- We recommend harvesting a EVS starter set of MVR from the HL7 NullFlavor and the CDC Draft Missing Values lists, and expanding the set based on caBIG CDE and use cases
- HL7 arranges NullFlavor values hierarchically, which the MVR Small Group has discussed, but for which the Group has not yet arrived at a recommendation

## Recommendation to Application Developers

- 	For each specific application/message context, is documentation of a MVR a requirement?
- If required, build the application to force MVR documentation
- If optional, build the application to accept MVR documentation, but not require it

## Recommendations to CDE Curators:MVR Implementation Methods

- There are two methods for implementing MVR:
- Include MVR values as permissible values for an individual enumerated CDE
- Create an associated MVR-CDE that enumerates MVR permissible values for an individual CDE
- Examples follow....

## 1 – MVR as CDE permissible values

- Gender – Permissible values
- Male
- Female
**Unknown**
**Not Specified**
- Lab Test Summary Result – Permissible values
- Normal
- Abnormal High
- Abnormal Low
**Pending**
**Not available from lab system**

## 2 – MVR as their own MVR CDEto be used when a ‘meaningful’ value is missing and a MVR needs to be identified and linked

- Gender CDE – Permissible values
- Male
- Female
- Gender MVR CDE – Permissible values
- Unknown
- Not Specified
- We are also considering a role for category MVR CDE, such as for physical exam findings or lab tests

## Other CDE Curator Recommendations

- Explicitness in value names is desirable
- “Uncertain disease progression” is more explicit than “Uncertain”
- “Uncertain” could mean that the data entry person was uncertain if disease progression was evaluated, an MVR
- Explicitness allows differentiation of a ‘meaningful’ value from an MVR
- Value meanings should be used to clarify the intent or role of MVRs
- When MVRs are included in CDE permissible value display lists, separate the ‘meaningful’ values from the MVR

## Differences in Perspective

- The MVR small group is not of one mind regarding the relative value of the two MVR implementation methods
- These differences represent different views
- regarding the degree to which the VCDE, and indeed caBIG as a whole, should be prescriptive v. descriptive in its standards
- regarding the role of architecture in the support of MVR functionality
- We have also not concluded our discussion of Recommendations to Application Developers

## Next Steps

- VCDE feedback on the recommendations so far and the strategic open issues
- MVR Small Group continues to clarify and describe the open issues
- MVR Small Group engages the VCDE and Architecture WS on resolving the open issues
- Wiki with us.....

## Wiki

- http://informatics.mayo.edu/wiki/index.php/CaBIG_Flavors_of_Null
- Username = wiki
- Password = wikiwiki
- Discussion, meeting minutes, decisions, use cases, links
- Editable off line and during meetings
- Need for housekeeping and concern with editing other author’s material
- Takes a little practice, but it doesn’t break