+--------------------------------------------------------------------+
 |                                                                    |
 |                           EVID DATA ITEM                           |
 |                                                                    |
 +--------------------------------------------------------------------+

 MEANING: Event Identification (EVID) data item for PREDPP
 CONTEXT: $INPUT record and NONMEM data set

 USAGE:
 $INPUT ... EVID ...

 DISCUSSION:
 EVID labels PREDPP's event identification (EVID) data item.  The event
 identification data item is required.  NM-TRAN can  supply  this  data
 item  if  dose  and  observation  events  are the only types of events
 present in the data.  EVID can have one of four values  in  any  event
 record.

 0    Observation  event.  The DV data item is an observation.  The CMT
      data item specifies which compartment is being  observed.   Dose-
      related data items (AMT, RATE, II, ADDL, SS) must be zero.

 1    Dose  event.   The  CMT  data item specifies which compartment is
      being dosed.  The DV data item is ignored.  One or more  of  AMT,
      RATE,  II,  ADDL,  SS  data  items must be non-zero to define the
      dose.

 2    Other-type event.  The DV data  item  is  ignored.   Dose-related
      data  items  must  be zero.  Examples of other-type events are: A
      compartment is turned on or off (CMT specifies which  compartment
      is  to be turned on or off); a prediction is obtained at a speci-
      fied time so that it may be displayed in a table  or  scatterplot
      (PCMT  specifies  the  compartment  from  which the prediction is
      obtained); some event occurs at a different time than any  obser- |
      vation or dose event, e.g. a covariate such as weight changes, an |
      intervention such as hemodialysis is started or stopped.

 3    Reset event.  The kinetic  system  is  re-initialized.   Time  is
      reset  to  the time of the event record, the amounts in each com-
      partment are reset to zero, the on/off status of each compartment
      is  reset  to  its  initial status.  The DV data item is ignored.
      Dose-related data items must be zero.

 4    Reset-and-dose event.  The system is first reset, and then a dose
      is given.  The DV data item is ignored.

 With  NONMEM  7, there is a change in the value of EVID under the fol-
 lowing circumstances:
 1) NMTRAN is appending EVID
 2) The record is not a dose event (AMT, RATE, SS = 0)
 3) MDV is present in the data set (i.e., was listed on $INPUT)
 4) MDV is 1 or MDV is 101                                              |

 Previous versions of NMTRAN always set EVID=0 (observation)  when  the
 record  was  not a dose event.  NMTRAN will now set EVID=2 (Other-type
 event) for this case.  Note that if the user supplies  both  EVID  and
 MDV, there is no change.  Similarly, if the user supplies neither EVID
 nor MDV, so that NMTRAN is appending both of them, there is no change.
 There  is  only  a change when the user supplies MDV but not EVID, and |
 has set MDV=1 or MDV=101 for non-dose records.

 With NONMEM 7.2 and higher, the "Repeated Observation Records" feature
 exists  to assist in specialized methodologies such as stochastic dif-
 ferential equations. A record in  a  data  file  may  be  set  up  for
 repeated  calls to PK and ERROR.  Each time, the same record is passed
 to PK and/or ERROR, but with a different  EVID.   The  user's  control
 stream  model  in  $PK  or $ERROR may then take advantage of executing
 certain code conditional on the EVID value.  For this  to  occur,  the
 user  must  introduce  one  or more of the following data items in the
 data file, with these names:

 XVID1 XVID2 XVID3 XVID4 XVID5

 These stand for "extra" EVIDs.  On the first  call  to  PK/ERROR,  the
 EVID is set to the value given in XVID1.  On the second call, the EVID
 is set to that in column XVID2, etc.  up to XVID5.  Only as many XVIDs
 as  are required are needed to be defined.  All the other items in the
 record do not change, except that if the present EVID used is  not  0,
 then  the MDV value is set to 1 for that call.  If an XVID is -1, then
 the call to PK/ERROR for that XVID is not made, nor for the  remaining
 XVIDs.   If  there  is an EVID column, the value in this column is not
 passed to PK/ERROR unless XVID1=-1 in which case a "normal" call  with
 that record occurs.
 (See stochastic differential equation example)

REFERENCES: Guide IV Section V.B
REFERENCES: Guide VI Section V.B


  
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