PARAM, AVAL, and AVALC

It is important to understand a key difference in approach between the SDTM Findings class variable --TEST and the ADaM BDS variable PARAM. SDTM --TEST is designed to work in conjunction with other variables called "qualifiers" (e.g., specimen type, machine type, body position) in order to describe the collected result. In contrast, the ADaM BDS variable PARAM does not have any accompanying qualifier variables. PARAM is the only variable that describes AVAL or AVALC. Qualifiers are not allowed.

PARAM is created to meet an analysis need, not just because something was collected. PARAM may describe an analysis value that is highly derived from subject data from any combination of SDTM domains of any class or classes, and/or any ADaM dataset. PARAM describes what is in AVAL or AVALC.

For most parameters, only AVAL or AVALC will be populated, not both. That both --STRESC and --STRESN are present and populated in SDTM Findings class domains does not imply that both AVAL and AVALC must be present and populated in BDS datasets. AVAL and AVALC have a different purpose than --STRESN and --STRESC. For example, for parameters corresponding to numeric tests in SDTM Findings class domains, it is not recommended to copy SDTM --STRESC into AVALC, because there is no analysis need for a character value. Further, doing so may result in breaking the one-to-one mapping requirement in some cases. If it is desired for traceability or listing purposes to bring the value of --STRESC into the ADaM dataset, the variable --STRESC may be copied as is without renaming it.

AVAL and AVALC are both populated only when one-to-one mapping may be useful, for example:

• When PARAM describes the numeric score of an individual question from a questionnaire, AVAL contains the score, and AVALC can be populated with the question answer text. Populating AVALC with the question answer text is supportive of review, and may help the consumer understand the meaning of the numeric score that is the subject of the Within the parameter, there is a one-to-one relationship between AVAL and AVALC on the rows on which both are populated.
• When PARAM describes a character-valued response from a set of possible values, the result is contained in If desired for ordering or other reasons, AVAL can also be populated, as long as the result of populating both AVAL and AVALC for the parameter is that they are a one-to-one map on the rows on which both are populated.