Quality control of a theme

The quality control works on the contents of the attribute table of one or more themes in a view. The purpose is to get statistics on the contents of the attribute fields, as well as to check the range of the attribute values. The following steps are involved

1. Select the theme(s) to control

2. Specify a table to store the outcome of the quality control

3. Specify the attribute table field(s) to be controlled

4. Specify legal value range of each attribute table field

5. Run the quality control

6. Report results

These steps are described in more detail in the following:

Select the theme(s) to control

Any active themes in the view will be quality controlled. If none are active, the user are asked to select one of the themes in the view.

Specify a table to store the outcome of the quality control

The user is prompted for a name of the file where the quality control results will be stored. The file will be created as a dBase table with the following fields:

Field The name of a controlled field

Type The type of the field

#Records Number of records in the table

MinLim The specified minimum limit of the legal value range

MaxLim The specified maximum limit of the legal value range

Min. Value The minimum data value in the field

Max. Value The maximum data value in the field

#values < MinLim Number of records with data value less than the specified minimum limit of the legal value range

#values > MaxLim Number of records with data value greater than the specified maximum limit of the legal value range

#Nodata The specified Nodata value

#Empty records The number of empty (without data value) records in the field

Specify the attribute table field(s) to be controlled

The user may choose to control all fields in the table, or one particular field. In the latter case the user is asked to select which field to control.

Specify legal value range of each attribute table field

For numeric fields, the user may specify the lower and upper limits of a legal value range, as well as a Nodata (Unknown/Undetermined) value. By default these values are nil, in which case any data value will be accepted as a legal value.

Run the quality control

In this step the value in each record in each field is checked and the various control parameters updated. For non-numeric fields only the Field, Type and #Records fields will be filled with information.

Report results

In this step, the table created in Step 2 is filled with the outcome of Step 6 and opened in a Table window so the results may be inspected.