Concepts of Parameter Lists

 

Content

Parameters and Parameter Lists

Data Sets, Data Items, and Replicates

Data Sets

Data Items

Replicates

Data Sets Versus Replicates

 
Related Topics

 

Parameters and Parameter Lists

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For the purpose of this discussion, we define a "Sample" as any single entity (typically a tangible quantity of a substance) that can be tested, whether independently or as part of a collective group.

By itself, a Sample essentially represents a reference to "something that must be tested". You cannot conduct tests on a Sample unless you associate it with a predefined set of variables that can hold data values that are recorded during Sample testing. A "Parameter" is such a variable, as it represents a single variable that holds a single data value.

Several hundred Parameters, each holding a single data value, would be neither a practical nor an efficient means of entering data. It is desirable to assemble Parameters into groups called "Parameter Lists". A Parameter List is a collection Parameters that share something in common and will be subjected to the same data presentation and manipulation rules. For example, a Parameter List called "Metals" could contain the Parameters Al, Ni, and Cu (each a metallic Sample).

In the most basic sense, the major functions of a Parameter List are to:

• Determine data to be entered or collected.
• Define how entered data are presented (such as define "Display Formats" to change the numerical format that is actually displayed in response to the entered data).
• Create "Parameter Limits" to define a set of numerical ranges and subsequently perform operations when an entered data value is within (or outside of) those ranges.
• Specify mathematical operations to be performed on entered data such as "Transformations" to modify entered data (such as truncate or round the value) and "Calculations" to perform arithmetic calculations on the entered data (such as add to or subtract from the value).
Other features of Parameter Lists include support for automatic calculation of the uncertainty of measure, Attributes (properties added to Data Sets to maintain additional information), and Version Approval (Parameter Lists are Versioned.
    Examples of what a Parameter List defines for each Parameter...
Parameter List Parameters Data Type Display Format Calculation Limit
Metals Iron Numeric Engineering Notation None <20
  Carbon Numeric Round to 2 significant figures None =20
  Steel Numeric Engineering Notation Al + Ni <40
Dimension Length Numeric Round to zero decimal places None <100
  Width Numeric Round to zero decimal places None =100
  Area Numeric Engineering Notation L x W <200

Three primary keys identify a Paramerer List:

Primary Key Description
ParamListId Unique identifier for the Parameter List.
ParamListVersionId Parameter Lists are versioned SDIs. This means you can have multiple versions of the same Parameter List.
VariantId A Variant is a copy of a Parameter List, associated with the same data as the original, but specifying different characteristics. Examples:
•A Company wants to collect two sets of data for a given Parameter List, each set reported in a different unit of measurement. In this case, a Parameter List might specify the Parameters in inches. A Parameter List Variant could specify these same Parameters in millimeters.
• A Project requires reporting environmental test conditions in two numerical formats. In this case, a Parameter List might specify test temperature and relative humidity in decimal notation to two significant digits. A Parameter List Variant could specify these same Parameters in engineering notation.

Each Parameter can also be associated with a "Parameter Type", which classifies Parameters according to some criteria. Examples:

• The Parameter Aluminum may have three types to indicate composition and grade: 1050, 2014, and 2024.
• The Parameter Dimension could have two types to indicate units of measurement: English and Metric.

Additionally, you can assign a "Parameter Alias" as an alternate name for a Parameter.  Aliases let you define a Parameter as required by each operation that references the Parameter.  For example, consider the following scenario:

a. Your company classically refers to a chemical as "benzene".
b. An instrument identifies benzene test data as "C6H6".
c. You prefer to identify it as "B" during data entry.

If you want to classify Parameter Aliases, you can specify the classifications in a System Reference Type called "Parameter Alias Type".  Using the previous scenario as an example, you might assign Parameter Aliases as follows:

Parameter Alias Parameter Alias Type Reasoning
C6H6 Instrument The Alias is relevant to an instrument.
B Entry The Alias is relevant to data entry.

 

Data Sets, Data Items, and Replicates

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Data Sets

 

A Parameter List is a generic entity and is not associated with a particular Sample. In order to use a Parameter List with a Sample, an instance of the Parameter List called a "Data Set" is created, and it is the Data Set that is associated with the Sample. A Data Set is therefore an instance of a Parameter List that is associated with an SDI.

Among other things, creating Data Sets allows re-use of the same Parameter List in different variations, as well as provides a subset of the Parameter List on which other operations can be performed. For example, some operations are performed at the Data Set level. This "instance" model is used in several areas of LabVantage functionality.

Example 1

Associating the Metals Parameter List with the SDI Sample-001 creates a Data Set:

Sample-001
Data Set
Parameter List Parameter
Metals Al
Fe
Ni
Example 2

The SDI Sample-001 has 5 Data Sets.  Two of the Data Sets are instances of the Metals Parameter List.  Each Data Set is always identical to the other, except that each is populated with different data. Three of the Data Sets are instances of the pH Parameter List.   Again, each Data Set is identical, except the Data Values. Note that a Data Value is defined as the numeric or textual value of a Parameter.

Sample-001
Parameter List Parameter Data Value
Metals Al
Fe
Ni 		1.7
4.3
6.6

Metals

Data Set 1
Al
Fe
Ni 		2.2
5.8
7.4

Metals

Data Set 2
Parameter List Parameter Data Value
Acidity pH 6.8

pH

Data Set 1
  pH 7.0

pH

Data Set 2
  pH 7.2

pH

Data Set 3

Each time you associate the same Parameter List with an SDI, the Data Set Number (integer) increments by 1, thereby indicating the number of Parameter List instances.

Data Items

 

The term "Data Item" refers to the combination of the entered data value for a Parameter, plus all information defined by the Data Set, including the Data Set's association with the SDI.  In the example below, two Data Sets are associated with Sample-001. Each Data Item is defined by a Parameter, Data Value, Data Type, Display Format, Calculation, and Limit:

Sample-001
Data Sets Parameters Data Value Data Type Display Format Calculation Limit
Metals Data Item Iron 2 Numeric Eng Notation None <20
  Data Item Carbon 4 Numeric Round None =20
  Data Item Steel 6 Numeric Eng Notation Fe + C <40
Dimension Data Item Length 10 Numeric Round None <100
  Data Item Width 12 Numeric Round None =100
  Data Item Area 120 Numeric EngNotation L x W <200

Replicates

 

A significant feature of the Data Set is the ability to create "Replicates", which let you conduct repetitive testing by entering multiple data values for a single Parameter in a Data Set. A Replicate is repeat data for a single Parameter in a Data Set.  Replicates allow you to enter multiple Data Values for a single Parameter in the same Parameter List.  Using the Metals Parameter List, you may have three values for Nickel.  In this case, each value is a Replicate:

Sample-001
Data Set Parameter Data Value
Metals Al 1.7    
  Fe 4.3    
Ni 6.6 Replicate of Ni
Ni 2.4 Replicate of Ni
Ni 9.1 Replicate of Ni

Data Sets Versus Replicates

 

An important distinction:

• Data Set Numbers track multiple instances of a Data Set.
• Replicates track repetitive measurements taken for a single Parameter in a Data Set.

 

Related Topics

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For more information regarding the concepts introduced above, see the following topics:

• The Parameter List Maintenance page lets you add and edit Parameter Lists.
• Parameter Limits define the status of Data Values, i.e., a Parameter Limit is either "met" or "not met".  
• Test Methods are containers that can host Parameter Lists, Specifications, and other Test Methods. When you add an instance of a Test Method (which is a "Test") to a Sample, you are adding these items to the Sample.
• Parameter List are Versioned SDCs.
• Approval Types let you specify rules used to Approve data.  When you associate Approval Types with a Parameter List, the corresponding rules apply to all Data Sets created from that Parameter List.