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For a given parameter within a BDS dataset, it is important (1) to be able to distinguish analysis values that are special cases of AVAL/AVALC (those for which the value is determined differently than the other analysis values within the parameter), and (2) to understand what method or algorithm was used to populate each special case. The variable DTYPE is to be used to identify records within a given parameter that contain these special-case analysis values. The value of DTYPE indicates the method used for populating the analysis value; a null value of DTYPE indicates the analysis value was not a special case. The metadata for AVAL (or AVALC) will give further information about the details of any algorithm or statistical method used to derive or impute these values. When the analysis value on a record within a parameter has been imputed or modified, DTYPE will indicate the method used to populate the analysis value. DTYPE would be used if there are special cases within the new parameter that should be identified. If a parameter is wholly derived, such as a Time-to- Event parameter, then it is a misapplication to populate DTYPE for all records in that parameter because, by definition, all records are derived using the same method.
Variable Name | Variable Label | Type | Codelist/ Controlled Terms | Core | CDISC Notes |
DTYPE | Derivation Type | Char | (DTYPE) | Cond | Analysis value derivation method. DTYPE is used to denote, and must be populated, when the value of AVAL or AVALC has been imputed or derived differently than the other analysis values within the parameter. DTYPE is required to be populated even if AVAL and AVALC are null on the derived record. Three common situations when DTYPE should be populated: · A new row is added within a parameter with the analysis value populated based on other rows within the parameter. · A new row is added within a parameter with the analysis value populated based on a constant value or data from other subjects. · An analysis value (AVAL or AVALC) on an existing record is being replaced with a value based on a pre- specified algorithm. DTYPE is used to denote analysis values that are "special cases" within a parameter. For each value of DTYPE, the precise derivation algorithm must be defined in analysis variable metadata, even for DTYPE values in the CDISC Controlled Terminology. The controlled terminology for DTYPE is extensible. ADD LINK See Section 4, Implementation Issues, Standard Solutions, and Examples for examples of the use of DTYPE. Some examples of DTYPE values:
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