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| NMPR17 |
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MEANING: NONMEM-PRED common
CONTEXT: PRED routine
USAGE:
COMMON /NMPR17/ F_FLAG
INTEGER F_FLAG
DISCUSSION:
When either of the options LIKELIHOOD or -2LOGLIKIHOOD appear in the
$ESTIMATION record, this indicates that for all observations, the
variable Y (with NM-TRAN abbreviated code) or F (with a user-supplied
PRED or ERROR routine) is being set to a likelihood (or -2 log likeli-
hood) value for the observation. Suppose, though, that neither option
appears. Then for a given observation, the default indication is that
Y or F is being set to a "prediction" of the observation. This is
equivalent to setting the variable F_FLAG to its default value of 0.
When, however, the variable F_FLAG is set to the value 1 (or 2) in the
PRED or ERROR routine, this signals that Y or F is being set to a
likelihood (or -2 log likelihood) value for this particular observa-
tion.
F_FLAG may be set in NM-TRAN abbreviated code.
IF (TYPE.EQ.1) THEN
Y=THETA(1)+ETA(1)+ERR(1) ; a prediction
ELSE
F_FLAG=1
A=EXP(THETA(2)+ETA(2))
B=1+A
Y=DV*A/B+(1-DV)*1/B ; a likelihood
ENDIF
A nonzero value of F_FLAG has no effect during a Simulation Step. But
note: When single-subject data are simulated for which, when the data
are later analyzed, Y (F) would always be set to a likelihood, and
when the ONLYSIMULATION option is used in the $SIMULATION record, then
usually the NOPREDICTION option can also be used. When the NOPREDIC-
TION option is used, if any eta's are used in the model, the data are
regarded as population data, but the model for the data in question
usually does not involve eta variables. When, however, single-subject
data are simulated for which, when the data are analyzed, Y (F) would
sometimes be set to a likelihood and sometimes to a "prediction", and
when the ONLYSIMULATION option is used in the $SIMULATION record, then
the PREDICTION option will need to be used (this is the default
option!). The reason is that the expression of residual variability
associated with the predictions will involve eta variables.
RESTRICTIONS:
When F_FLAG is set to a non-zero-value for some observation, neither
the LIKELIHOOD or -2LOGLIKIHOOD option may be used.
When F_FLAG is set to a nonzero-value for an observation, the Lapla-
cian estimation method must be used.
Unless with all observations within an individual record, F_FLAG is 0,
the RES and WRES items will be 0 for all data records in the indivi-
dual record.
When F_FLAG is set to a nonzero-value for an observation within an
individual record, inter-L2 correlated epsilons are not allowed with
the observations within the individual record. (See nmprd5)
If the data are population data, a nonzero value of F_FLAG cannot be
used within a multiple-observation L2 record. If the data are
single-subject data, a nonzero value of F_FLAG cannot be used within a
multiple-observation L1 record.
REFERENCES: None.
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