Introduction to information systems T. Cornford, M. Shaikh is1 060 2013

Reading activity
Read Chapter 7, Section 7.2 of Curtis and Cobham (2008) and Chapter 12, Section 12.3 
of Laudon and Laudon (2013). 
The aim of this assignment is to demonstrate an understanding of the basis 
of undertaking analysis and design for a spreadsheet, as well as to provide 
evidence of the use of some of the main features of a spreadsheet package. 
Spreadsheets are tools used for analytical modelling purposes; namely, 
the description of a situation by a set of quantifiable variables and their 
relations. One of the most common uses of spreadsheets is in accounting 
practices − for example, the calculation of the balance sheet of a company. 
However, spreadsheets have proved useful in a variety of contexts 
including, for example, project management, engineering, geology, 
statistics and operational research. From a management perspective 
spreadsheets can be seen as a type of decision support system (DSS) (see 
also Chapter 3 of this guide). 
For this assignment we recommend that you approach it broadly as a 
decision support system intended to help somebody to use some data to 
make a decision or to gain some extra insight, rather than as a simple 
structured descriptive report like a balance sheet. 
What we mean by this is that the spreadsheet should be able to help 
somebody by manipulating or modelling some data (you could say ‘playing 
with’ some data) and allowing the user to input their own choice of 
variables or parameters in order to assess the resulting outputs.
The basis of a spreadsheet developed in this style will be an analytical 
model that relates different types of data (probably mostly numerical data) 
in order to offer some insight. 
Such a model may be built in six steps: 
1. Framing the problem.
2. Identifying the variables and parameters that describe the problem – 
the input to the model.
3. Quantifying as many of these variables and parameters as possible.
4. Specifying the relations among variables and how they combine – in 
other words, the model you will use.
5. Specifying the required output from the model in terms of a user’s 
interrogation of the model – reports.
6. Testing the spreadsheet with carefully chosen data and identifying and 
correcting errors.

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Chapter 2: Preparing for the project work
27
Curtis and Cobham (2008, pp.236–38) provide a very useful brief design 
methodology for a spreadsheet along these lines, distinguishing five 
elements: 
1. user information
2. input data 
3. logic (for example, the model)
4. report (what the user wants to see or know)
5. errors. 
The word ‘methodology’ is used to describe a framework for undertaking 
some task, combined with some tools to be used. In information systems, 
and in particular in development of systems, methodologies are often 
proposed, adopted and critiqued. In this case the methodology being 
proposed is contained in the two lists given here – one a set of sequential 
and necessary tasks, the other a proposed general structure or template for 
the spreadsheet itself. 
In the example in Curtis and Cobham (2008), worksheets and the 
workbook feature of the Excel spreadsheet package are used to specify a 
separate worksheet for each of these five elements. Doing this may seem 
too complex for a simple project, but it can help you to concentrate on the 
core distinctions between input data, model and output.
The benefits of analytical modelling flow from the ability of the user to 
adjust and interrogate the model. Therefore, flexibility and robustness are 
required qualities for the model. A great deal of good modelling practice 
when developing spreadsheets is incorporated in the two fundamental 
laws of spreadsheet modelling. 
• The first law specifies that any cell on the spreadsheet should contain 
either a variable (number or text string) or a formula, but never a