4. Rules

Whenever someone needs to do something specific, they follow a set rules.

These rules may only be in their head or they may have them written down.

If they are written down, then someone else can also carry out the same task and get a sensible result.

Example

A spreadsheet model has been set up so that staff working at a plumbing company can quickly create a price quotation when a customer rings up to find out how much it will cost them to have a new bathroom fitted.

It is important that anyone answering the phone follows the same set of rules when using the spreadsheet model, otherwise customers might be given different prices.

Someone has prepared a set of rules for all staff to follow when using the model:

1. Enter the customer's name in cell B1
2. Enter a starting price for the job in cell A3
3. Is the customer entitled to a discount? If yes, go to step 4, if no go to step 5
4. Set the correct discount in cell B6 (Do not enter a discount greater than 20%)
5. Read out the quotation price for the customer from cell A1.
6. Save the spreadsheet quotation with the quotation number and customer surname as the file name e.g. 829_Jones.xls

Notice that item 4 is telling you not to enter a discount of no more than 20%. This rule can be built in to the model by using the data validation feature. Data validation constrains entered values to be within certain limits set by a data validation rule for that cell. If a value falls outside the limits then an error message is displayed.