Steps in designing a spreadsheet solution

AnalysisDesign the solutionImplement the solution and test itRefinement and Maintenance

Task ExampleTask Example

Analysis

Attempt to identify and understand the problem

How will the numbers get into the spreadsheet? Will the user type them into the appropriate cells or should a dialog box be used?

How should the output be displayed? How many decimal places should be displayed in the

answer? How should the numbers be formatted for display?

N.B. Never make assumptions! Ask as many questions as are needed to completely understand what the client wants!!!

Steps

Design the solution

Draw a pen and paper model of the spreadsheet

Identify your sources of data Plan the user interface Develop the formulae that you will use Test your design solution Keep the client updated by showing your

plans.

Steps

Implement the solution

Build the spreadsheet Test the spreadsheet (working prototype)

N.B. It is important to test every aspect of the spreadsheet, e.g. if you are using the IF function or LOOKUP function, all possible combinations should be tested.

Show the working spreadsheet (prototype) to the client for feedback.

Demonstrate it by using some of the test data you created.

Steps

Refinement and Maintenance

REFINEMENT Improvements may

be requested. External factors

(e.g. changes to Tax system, like GST).

After the client agrees with the solution, there may still be work to do:

MAINTENANCE Well designed spreadsheets

and constructed are usually easy to maintain.

Time and effort invested up front is beneficial as changes may be difficult and costly to make

Steps

Modelling a pricing system for a school disco

TASK You’re on a committee given the responsibility of

organising the next school disco There will be certain expenses Money can be made from sales of tickets, drinks & chips Work out how much to charge for these things so that a

reasonable profit is made

Analysis Designing the Solution Implementing the solution Refinement & Maintenance

Task Analysis

ANALYSIS 1 - PricingDetermine the prices for: Tickets Drinks ChipsProblem: Work out how to make

$1000 profit to put towards equipment for the music department

If the prices are wrong: Won’t make enough

money for the music equipment

Make too much money, in which case the students (who you represent) will have paid too much!

ANALYSIS 2 - QuestionsSpreadsheets are well suited to this task.

Consider the following questions: What data will be input into the system? What calculations should be performed? What form should the output take?

ANALYSIS 3 - Model (Input/Output)The model should allow changes to the input

to be reflected in the output:INPUTS

Cost of the disco equipment Cost of hiring the hall Cost of advertising and printing tickets Purchase prices of the drinks and chips The total number of tickets, drinks & chips sold Prices that will be charged for tickets, drinks &

chips.

Task ExampleTask Example

Task Design Construct a Pen & Paper model before

attempting the electronic solution

Di sco costs a n d profi ts Costs a n d i n come Other Pa ra meters Costs No. of Sa les Di sco & DJ $$$ Ti ckets NNN Hi re of Ha l l $$$ Dr i n ks NNN Soft Dr i n ks $$$ Chi ps NNN Chi ps $$$ Pr i n ti n g $$$ Cost Pr i ces Tota l Costs $$$ Dr i n ks $$$ Chi ps $$$ I n come Sel l i n g Pr i ces Sa les of ti ckets $$$ Ti ckets $$$ Sa les of Dr i n ks $$$ Dr i n ks $$$ Sa les of Chi ps $$$ Chi ps $$$ Tota l I n come $$$ Tota l ; Profi t/Loss $$$

Disco Costs & Profits

Costs & Income Other ParametersCosts Number of SalesDisco & DJ TicketsHire of Hall DrinksSoft Drinks =F7*F11 ChipsChips =F8*F12

Printing Cost PricesTotal Costs =SUM(C6:C10) Drinks

Chips

Income Sales)Tickets =F6*F15 Selling PricesDrinks =F7*F16 TicketsChips =F8*f17 Drinks

Total Income =SUM(C14:C16) Chips

TOTAL Profit/Loss =C17-C11

Create a draft electronic spreadsheet from the P&P design

Develop the formulae for the figures that need to be calculated by the spreadsheet

Lock Formulae Experiment and test

Task ExampleTask Example

Task Implementation

Once we’re happy with the design, it is time to build the spreadsheet Verify the solution using all sets of test data Compare it to the output expected

Disco Costs & Profits

Costs & Income Other ParametersCosts Number of SalesDisco & DJ 155.00$ Tickets 300Hire of Hall 200.00$ Drinks 350Soft Drinks 157.50$ Chips 250Chips 62.50$

Printing 75.00$ Cost PricesTotal Costs 650.00$ Drinks 0.45$

Chips 0.25$

Income Sales)Tickets 1,200.00$ Selling PricesDrinks 350.00$ Tickets 4.00$ Chips 250.00$ Drinks 1.00$

Total Income 1,800.00$ Chips 1.00$

TOTAL Profit/Loss 1,150.00$

MORE TESTING What if fewer students attend

than originally thought? What would happen to the

figures The expenses stay the same To maintain profits, the selling

prices would have to rise

Task ExampleTask Example

Task Refinement & Maintenance

As you build the spreadsheet, ask yourself how the model could be improved

Are there other inputs that could be considered or other results calculated?

You might consider displaying the results graphically

Finally, remember to document any changes you make

Task ExampleTask Example

Bibliography

Title: Information Processes and Technology

(HSC Course) Authors: Peter Ware, Paul Cheleski & Bill ChiversPublished by: Jacaranda (jaconline.com.au)