The Comparison Observations dialog box is used to specify the difference between two calibration observations as another calibration observation for PEST. To display the Comparison Observations dialog box, select Model|Edit Comparison Observations... PEST must be activated to display the Comparison Observations dialog box.
Sometimes, the difference between two observations is more useful than the observation values themselves in calibrating a model. For instance, you can define a head gradient as a calibration observation by computing the difference in head between two locations. Another useful difference observation would be the difference in head between measurements made at two different times at the same location. Such comparison observations can be defined in the Comparison Observations dialog box.
The dialog box has a table with 7 columns.
Observation Name (OBSNME) is the name of the comparison observation.
Observation Group (OBGNME) is the name of the PEST observation group to which the observation is assigned. Observation group names are specified in the Pest Properties dialog box. Observation group names can be be assigned later in the Pest Properties dialog box if a suitable observation group has not yet been defined.
First Observation (OBSNME1) is the name of the first observation that will be compared.
Second Observation (OBSNME2) is the name of the second observation that will be compared.
Observation Value (OBSVAL) (OBSVAL1 - OBSVAL2) is the observed difference in value between the first and second observations. It is computed as value of the first observation minus the value of the second observation.
Observation Weight (WEIGHT) is the weight assigned to the comparison observation.
Comment is an optional comment about the observation.
