Value Description

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Value Description Value Documentation
Course Paris March 07
Mark Roe Institute of Food Research WP1.8
Compiler Network and Supporting Task Groups
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Value Description

• Information required for a value related
  to a food component, including
• Value description
• Associated statistics
• Method documentation
• Value reference documentation
• Quality index rating

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Linked documentation fields

• Value description includes links to codes
  describing
• Food
• e.g. 19-425 ( Spaghetti Bolognase)
• contributing food ID
• 19-352 Bolognase sauce (with meat)
• 11-453 Spaghetti, white, boiled
• Component
• e.g. SE ( Selenium)
• Method
• Value Reference

May be multiple if value from aggregated data
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Basic value fields

• All required fields
• Selected value (Best location)
• Best representative value according to the
  compiler
• May not always be possible to assign selected
  value e.g. when there are clusters of values
• Value should be quoted to appropriate significant
  figures
• Unit
• From unit thesaurus
• Matrix unit (mode of expression)
• From matrix unit thesaurus
• Value type
• Describes characteristics of the selected value.
  From value type thesaurus

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Unit thesaurus
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Matrix unit thesaurus
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Value type thesaurus
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Value reference fields

• Normally optional single set of fields.
• Multiple sets of value reference fields, with
  associated sets of value method fields, may be
  used for values aggregated from different
  sources.
• Acquisition type
• From acquisition type thesaurus describes basis
  for including value in database
• Value reference
• Links to reference reporting the original source
  of the selected value
• Value food identification code
• Used when value reference is a food composition
  table
• Value recalculation flag
• Indicates that value reported in value reference
  has been recalculated, e.g. conversion of units
  or matrix unit

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Acquisition type thesaurus
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Statistical value fields

• Number of samples (n)
• Number of analytical samples contributing to the
  statistic, e.g. number of analyses of different
  samples, number of values from different sources
• Mean (arithmetic)
• use for normal distributions
• Median
• Use for skewed distributions
• Standard deviation (normal distributions)
• Standard error (s / ?n)
• Minimum
• Maximum

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Additional value fields

• Quality index
• Under development (WP1.3)
• Date of generation
• Date of documentation
• Required when values documented retrospectively
• Remarks

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Contributing values

• Contributing values may refer to
• A value which is aggregated from a number of
  contributing values for the same component from
  different sources, e.g.
• average of values from different food
  composition tables
• A value which is derived from values for one or
  more different components, e.g.
• protein calculated from total nitrogen and NCF
• Total sugars calculated from summation of
  individual sugars
• Contributing values for calculated derived values
  should be available and documented

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Additional entities

• Optional entities used to document values
  contributing to derived or aggregated values
• Contributing values
• Used when documentation of original contributing
  values available, properties include Value ID,
  Contributing value ID, Weight, Remarks
• Statistical values
• Holds all values relating to a statistic. Used
  when documentation not available for contributing
  values. Properties include Value ID, Value,
  Weight, Remarks