P&S Monthly April 25, 2006

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Contents

Four Main Quality Dimensions

  1. instrument accuracy
  2. platform
  3. environmental effects
  4. data processing

Subdimensions of each dimension

  1. Focus on end use--how well is it received (by ESIP Cluster, decision maker)
  2. What words should be used to break down into a second tier ten-scale in each Main Dimension?
  3. How much will it depend on each context of the data collection and use?
  4. Ease of use by decision support systems
  5. Issues of availability, accessability, reliability
  6. Educational ratings may be separate (age appropriateness, curriculum, etc)


One simple set of criteria

science-ready="A"
commercial-ready="C"
education-ready="B"

I saw the following in reference to astronomical data quality, but could be equally applicable: A=Data are fully calibrated, fully documented, and suitable for professional research. B= Data are calibrated and documented, but calibration quality is inconsistent. Users are advised to check data carefully and recalibrate. C= Data are uncalibrated. U= Data quality is unknown. If a resource does not provide a data quality assessment, class U should be assumed.


Reference: Resource Metadata for the Virtual Observatory, Version 1.01 G. Major

Use of the Quality Assessments

Is it risk or degree of confidence?

Related to use in making decisions--there the decision maker needs to determine level of risk aversion appropriate--relates to the cost to a business of making a "bad" decision

Maybe we can provide guides-to-use for these assessments

Might be useful even to have a simple five-star system. This might be all that is needed for one category of user--whereas other areas of research might want much more.

Building the Assessments Database

Testing

Under what conditions was it tested? Lab, over time, multiple sites and situations

Surveys Peer review Recording voluntary user responses Statistics (variability, covariance across studies, Bayesian causality) (Bruces work)


Strategy for getting the assessments entered

Simple assessments can come from the providers themselves

How do we come up with incentives and tools to assure that the provider will/can do this?
Could we use some measure of data quality to determine how aggressively to promote certain products?
Might be sufficient to simply set the criteria by which a provider receives the ratings (stars or ranking from 1-10)

Assessments might also come from the users

Might be related to number of responses
We could simply report numbers of positive and negative comments
Survey of users: accessibility, usability
If you require people to comment, you may lose users.

Survey of ESIPs

might even pay for people to review

Data access vs reliability/quality issues

Federation might only talk about reliability and leave quality to provider

Role of the Clusters

This may be the driver for ESIP participation
The Societal Benefit Clusters might take over the rating in each domain




Edits to Discussion from March 28, 2006

Objective

Create a common set of data quality metrics across all Federation data products. Data providers can provide measures for their own products. 3rd parties can provide their own ratings. Quality can refer to accuracy, completeness, and consistency. It is not clear how to measure consistency. It is desirable to provide quality assurance.

We would like to create a 1-10 Data quality scale, where:

 1 = no accuracy claimed
10 = fully reliable data that has withstood the test of time

This measure can be applied to any of the quality dimensions:

Quality Dimensions

  1. Sensor/Instrument (well calibrated, stable, checked across instruments, V/V)
  2. Spacecraft (locational and communication accuracy)
  3. Environment Issues (contamination from clouds, rainfall, ground, sea, dirt, etc.)
  4. Data Processing (accuracy of interpolation, algorithms, ancillary source data)

Our Task

Create a 1-10 scale for each dimension. We will work with Federation members to associate a quality description with each value.


Other topics

Quality assurance (someone tags it as valid)
Useful metadata provided?
Instrument Verification and Validation
Data processing
Re-processing tag and notification
input errors and forcings
re-gridding
missing data
Usage issues
High enough resolution?
Valid inference about what is measured
Chain of Custody (for legal use)

Completeness Can we come up with categories of data completeness?

3rd party ratings

NCDC
NCDC Certified data (only states that it is in the archive -- designates as official, not a quality statement)
Dataset docs use FGDC quality section, with different levels of detail
GCMD
DIF records have some minimum required fields to accept
then have a text field to describe quality
ECHO
"measured parameters" from ECS model
QA percent cloud cover; missing pixels;
CLASS/Climate Data Record
Maturity Model approach for data (John Bates application from software maturity)
Level of maturity (five levels of improved treatment)
See CDR Maturity paper
FGDC
Whole section on quality, text only
Testimonials
Peer review

Discussion

Completeness

  • Is this a measure of quality?
Depends on stated offering from the provider; if they claim it is complete and it isn't

Assertions about datasets

We may want some standard for claiming and measuring how valid a claim may be


Additional Questions

  • What common data quality standards can the Federation offer within the Earth Information Exchange?
  • How can we enforce these standards within the Earth Information Exchange?
  • Are there similar ratings for "data services"?

Action

Rob will send advertisement to the whole group for next months meeting.

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