Parameter Limits, Parameter Limit Types, and Limit Rules
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Concepts of Parameter Limits |
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Parameter Limits, Parameter Limit Types, and Limit Rules |
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Parameter Limits |
"Parameter Limits" can be defined for a specific Parameter List. A "Parameter Limit" defines a set of numerical ranges, along with a set of conditions that do certain things when entered data falls within (or outside of) those ranges. For example, "Transformations" can be applied to modify entered data (such as truncate or round the value), or an operation can be performed if the limit check fails (such as send an email). Two methodologies are available for checking entered data against a Parameter Limit:
| • | "Standard" Parameter Limit Checking provides an indication of
whether or not a limit is met. For example, the data could be identified
as "Passed" when the limit is met and "Failed" when the limit is not met.
To perform a Standard check, you must create Parameter Limit Types. |
| • | "Extended" Parameter Limit Checking performs operations that
depend on the entered data value. For example, when the limit is met (or
not met), you could modify the value and its display format, then execute
an Action.
To perform an Extended check, you must create Parameter Limit Types and Limit Rules. |
Parameter Limits are not intended to provide an indication of data integrity or quality. Specifications are provided for that purpose.
Parameter Limit Types |
To qualify Parameter Limits, "Parameter Limit Types" define the boundaries of the numerical Parameter Limit ranges (such as "Lower" for "less than 20", "Upper" for "greater than 30"), and define "Conditions" for the Parameter Limit (such as "Pass" if "less than 20", "Fail" if "greater than 30"). For example:
| • | Two Parameter Limit Types called "Lower" and "Upper" could define minimum and maximum Parameter Limits. |
| • | To characterize two elements, you could create a Parameter Limit Type called "Qualified". Next, associate "Qualified" to both the Parameter Al (having a Limit of <20), and the Parameter Au (having a Limit of >50). "Qualified" then defines Al values less than 20, and Au values greater than 50. |
Limit Rules |
Parameter Limit checks can be extended by applying a "Limit Rule", which redefines the conditions defined in the Parameter Limit Type. For example, when a Parameter Limit is met, a Parameter Limit Rule can:
| • | Modify the entered value and its display format. |
| • | Assign a Data Item Condition to the entered value. |
| • | Execute Actions. |
Defining Parameter Limits |
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Standard Parameter Limit Checking: Parameter Level |
"Standard Parameter Limit Checking" uses Parameter Limit definitions you specify for each Parameter in the relevant Parameter List. As you enter data for each Parameter, entered data is checked against Parameter Limits using the following information you define for the Parameter List:
| • | You must define a Parameter Limit for each Parameter in the Parameter List. Next, add a Parameter Limit Type. Finally, assign the Limit Type to each Parameter. |
| • | Optionally, you can apply "Transformation Rules", which are mathematical expressions that define transforms applied to data during data entry. For example, while entering data in the Data Entry Page, a Transformation Rule could round a number to a specified number of decimal places, or add a number to the entered value. |
| • | As an additional option, you can specify a Task (Action, its Properties, and scheduled execution time) to perform if a Parameter Limit is not met. |
The illustration below shows how Standard Parameter Limit Checking can be applied to entered data.
| 1. A User enters 19.5 | 2. The Lower Limit is met. | 3. The Data Item Condition is set to "Pass". | ||||||||||
| Data Entry | "Metals" Parameter List | Parameter Limit Types | ||||||||||
| Sample | Data Set | Parameter | Data Value | Parameter | Parameter Limit | Parameter Limit Type | Parameter Limit Type | Parameter Limit | Limit Type Status | Data Item Condition | ||
| Sample-001 | Metals | Au | 19.5 |
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Au | <20 | Lower |
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Lower | <20 | Met | Pass |
| >30 | Upper | Upper | >30 | Not Met | Fail | |||||||
Extended Parameter Limit Checking: Parameter List Level |
If you require further definition of Parameter Limits in a Parameter List, you can add a Limit Rule to re-define one or more Limit Types in the Parameter List. Limit Rules can apply any or all of the following additional data modifiers and Parameter Limit definitions to each Limit Type, either unconditionally, or depending on whether a Parameter Limit is "met" or "not met":
| • | "Transformation Rules" can be applied as described in "Standard Parameter Limit Checking" above. |
| • | The "Display Format" of the data can be changed. |
| • | You can specify a "Data Item Condition" Reference Type that you have previously added to define the condition of a Data Item (such as "Pass" or "Fail"). |
| • | A "Parameter Limit Qualifier" can also be specified. This is an alphanumeric string that you enter to define a classification of data. For example, MDL (method detection limit) could represent a Parameter Limit Qualifier that, when combined with a Parameter Limit Value and Operator such as <10, re-defines the Parameter Limit as <10;MDL. |
The illustration below shows how Extended Parameter Limit Checking can be applied to entered data.
| 1. A User enters 19.5 | 2. The Lower Limit is met. | 3. The Data Item Condition is set to "Pass". | |||||||||||||||||||||||
| Data Entry | "Metals" Parameter List | Parameter Limit Rule | |||||||||||||||||||||||
| Sample | Data Set | Parameter | Data Value | Parameter | Parameter Limit | Parameter Limit Type | Parameter Limit Type | Apply When | Apply Transform | Execute Action | Data Item Condition | ||||||||||||||
| Sample-001 | Metals | Au | 19.5 |
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Au | <20 | Lower |
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Lower | Limit is Not Met | (Data Value) + 20 | Send Email | Adjusted | ||||||||||||
| >30 | Upper |
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| 4. Data Value changed to
39.5
5. SendMail Action is executed. 6. Data Item Condition is "Adjusted". |
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Additional Information |
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Deferring Transforms |
For each Data Item, you can defer (suspend) application of all Transformation Rules, whether they are applied to the Parameter List or the Limit Rule.
Limit Types for Parameters and Specifications |
The same Limit Type SDC is used to define both Parameter Limits and Specification Limits. When you add a Limit Type SDI, the Limit Type Maintenance Page offers a choice of whether you want to apply the Limit Type to Parameters or Specifications. To distinguish from Parameter Limit Types, this documentation uses the term Parameter Limit Type to describe Limit Types that define Parameters.
Extended Limit Strategies |
In the Limit Rule Maintenance Page, you can define extended limit strategies for one or more Parameter Limit Types. For example, each Parameter Limit Type can define additional transformations of data values, or execute Actions based on whether or not the Parameter Limit is met.
Parameter Limits Versus Specifications |
Parameter Limits are not intended to indicate of the quality of measured values. Parameter Limits are used to execute another operation if the Data Value exceeds the limit. Parameter Limits are defined in a Parameter List. Each limit is associated with a Parameter.
Specifications are intended to indicate the quality of measured values. Exceeding a Specification Limit provides an "in spec" or "out of spec" indication. Specifications are not defined in a Parameter List... they are associated with an SDI.