The design consists in a single table, voters, compressing all the information needed. This is possible due to the use of coded domains inside the geodatabase in ArcGIS.
The table contains the following attributes:
| Field Name | Field Type | Field Size |
|---|---|---|
| VoterID | Number | Long Integer |
| PIN | Text | 12 |
| EthnID | Number | Integer |
| PartyID | Number | Integer |
The VoterID represents the identification of the voter. For this variable a long integer number was selected. The maximum of a long integer value is 2,147,483,647 which allows for Id numbers of up to 9 digits. Its storage size is 4 bytes. For this field the null values were allowed to include persons that don’t want to be identified but filled out the rest of the form.
The PIN field is the tax parcel ID number of the voter's residence. The field type is text in order to accommodate alphanumeric characters including the dash. This field storages up to 12 characters. In this field null values are not allowed because without the PIN it is not possible to locate the voter’s home and therefore to use the entry in the spatial analysis.
The EthnID field is the Ethnicity of the voter. For this variable an integer number was selected. The maximum of an integer value is 32767. Its storage size is 2 bytes. The null value was allowed for this field to include people that don’t know or don’t want to declare its ethnicity and its is important to differentiate between null and others. An important characteristic of this attribute is that it was associated with a domain which permits to associate a code (coded domains) to a value. For this variable the coded domain was called Ethnicity with the following values:
The PartyID field is the Party Affiliation of the voter. For this variable an integer number was selected. A coded domain called Party was associated to this variable. Null = no. The values of the domain are:
For this variable the group undecided was added in order to capture the undecided voters that can be targeted with an especial campaign.
The use of coded domains for the EthnID and PartyID fields clearly lessen the effort required for entering the data into the table by displaying a list from where the person selects the corresponding value. Besides, the use of coded domains also decrease the chance of data entry mistakes by restricting the values allowed into the table. Another advantage of the design of these two fields is the use of integer data type to reduce the file storage to just 2 bytes per entry.