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| L2 DATA ITEM |
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MEANING: Level Two (L2) data item for NONMEM
CONTEXT: $INPUT record and NONMEM data set
USAGE:
$INPUT ... L2 ...
DISCUSSION:
L2 labels level-two (L2) data items. The level two data item is
optional.
Recall that the ID data item is used to group together the data
records containing observations which have the same realization of the
level-one random effects (etas). Similarly, the L2 data item is used
to group together the data records containing observations which have
the same realization of the level-two random effects (epsilons). The
observations of such a group is called a level-two observation. The
group itself is called a level-two (L2) record. Data records of an L2
record must be contiguous (and contained within the same individual
record). By default, level-two observations are treated as being sta-
tistically independent multivariate observations. (However, within a
level-one observation, the level-two random effects can be made to be
correlated between level-two observations.)
Here is an example of a fragment of a data set using L2 data items.
There are two types of observations, designated by the two different
values of the user data item TYPE. Note that the L2 data items are
the same for both of the observations at TIME=2, and they are also the
same for both of the observations at TIME=112.5.
ID TIME AMT APGR WT DV TYPE L2
1 0. 25.0 1.4 7 . . 1
1 2.0 . 1.4 7 6.0 1 1
1 2.0 . 1.4 7 17.3 2 1
1 12.5 3.5 1.4 7 . 2 2
1 24.5 3.5 1.4 7 . 2 2
1 37.0 3.5 1.4 7 . 2 2
1 48.0 3.5 1.4 7 . 2 2
1 60.5 3.5 1.4 7 . 2 2
1 72.5 3.5 1.4 7 . 2 2
1 85.3 3.5 1.4 7 . 2 2
1 96.5 3.5 1.4 7 . 2 2
1 108.5 3.5 1.4 7 . 2 2
1 112.5 . 1.4 7 8.0 1 2
1 112.5 . 1.4 7 31.0 2 2
When the data are single-subject and the L2 data item is defined to
NM-TRAN in a $INPUT record, the ID data item is taken to be the L2
data item. The ID item may be defined, but then it is not in turn
identified to NONMEM as such. The labels L2 and ID (if defined) may
be used in abbreviated code, and then they refer to the corresponding
items of the data record, as specified in the $INPUT record. However,
if the user uses the label L1 instead of the label ID, or uses the
label L1 as a synonym with the ID label, then NM-TRAN does not change
the designations: For NONMEM, the items labeled L1 are taken to be the
ID data items, and the items labeled L2 are taken to be the L2 data
items.
REFERENCES: Guide II Section D.3.3
REFERENCES: Guide V Section 12.4.2, 12.5
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