Key Competencies
Thinking, relating to others, participating and contributing
Go to topConceptual Model
Prior Knowledge
Students will already have created a data store for the employee records. This could be a spreadsheet, CSV file or a database table. For these lessons the data store will be a table in a MS Access database.
Go to topLearning Outcomes
On completion of this lesson you will know how to describe the requirements of a user interface without any reference to how that that interface is to be implemented.
Go to topIntroduction
Prior to creating a database we must first sit down and determine what we need to use the database for. In our case we will look at creating a database for an organisation to keep track of its employees. Our first task, therefore will be to sit down with members of that organisation to determine what data they want to store regarding their employees. We also need to know what this data is to be used for and whether it is numeric, text or otherwise.
We may need more than one meeting to determine the full nature of the database. HOwever, once we reach a point where the organisation is happy with the design of the dataase we can proceed with building the database itself.
For the purpose of this course we will assume that the organisation requires a very simple database that contains one table only. A real life database would usually have a much larger number of tables
Go to topThe Conceptual Model
The application for which a user interface is to be created involves creating and maintaining employee records for an organisation who pays their employees on an hourly rate.
Regardless of the storage type the data items that are required are: employee number, IRD number, name, address, phone number, start date for employment, finishing date of employment, employee’s hourly rate, their tax rate , name of the department to which they belong and whether or not they are current, i.e. currently employed by the organisation.
Based on this data the students, either individually or in groups, will attempt to create a conceptual model of the user interface. This will involve determining:
- what data is required and what are the constraints on that data
- what activities/processing are to be carried out on the data
- how to ensure that the processed data is correct
According to good practice, at this stage there will be no specifications regarding how the processing, the constraints or ensuring the correctness of the data is to be carried out (Johnson J. , 2008, p. 20).
After this brainstorming the class should form a plan for the conceptual model.
The activities carried out on the data should be broken down to:
- Entering new employee records
- Editing existing records
- Removing records of employees who have left
The following table shows the specifications for the data that is to be used for the application.
| Field Name | Discussion |
|---|---|
| Employee Number | This field is solely used to identify each employee. It is to be numeric and is to be automatically incremented by 1 for each new employee. |
| IRD Number | The format of this data item is determined by the Inland Revenue Department. For this reason, it must contain exactly 8 numeric digits. Although numeric, no mathematical calculation is to be performed on it. As no two employees should have the same IRD number, each value in the table must be unique. |
| Full Name | Impossible to check this for errors |
| Commencement Date | This must be clearly shown to be a date |
| Finishing Date | Same as above |
| Address1 | Difficult to check this for errors |
| Address2 | Difficult to check this for errors |
| Contact Phone | Restrict it to landline numbers. Use area code followed by number. Both parts should be visually identifiable. Area cod will be enclosed in brackets. |
| Hourly Rate | Values less than 20 and greater than 80 will not be allowed |
| Tax Rate | Only the values 5, 10, 15 and 20 are allowed. All other values must be rejected. |
| Department | Only the values “Customer Service”, “Online orders”, “Accounts”, “Confectionary”, “Fruit & Veg” and “Bakery” will be accepted. |
| Current | Is the person still employed or have they left. Either yes or no. |
The processing is specified as follows.
Adding new employee records will involve adding all of the above data items apart from Finishing Date and Current. It will also involve ensuring the entered data complies with the constraints specified above.
Editing existing employees will involve changing the values of one or more of the following data items: name, the two address items, phone number, hourly rate, department and tax rate. The same restrictions for ensuring correct data will be applied here as in processing a new employee.
Removing records of employees who have left. Here the records will not actually be deleted. They will simply be marked as not current and the date the employee left inserted into the field Finishing Date. No other data item is to be modified.
The conceptual model, when finalised, must be the guiding document for the HCI project until it is completed (Johnson J. , 2008, p. 24). It is important that all aspects of the UI refer back to it, otherwise people may lose sight of it and thus develop a UI that performs differently to what they expected. (Norman, 2013)
Go to topSummary
The conceptual model specifies the data to be used in the application, along with its constraints. It also specifies the processing that is to be carried out on that data.
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