Spreadsheets and Business

Why the popularity of spreadsheets?

• “End user Computing”

• Long delays for IS department to do analysis and reports

• Ease-to-use, powerful software

• No need to wait for that overworked professional programmer

• Now - anyone can write software to do business analyses

There’s the Rub…….• Critical business analyses is being done

by amateurs• Think about …. How

dependent business is on spreadsheets and

How little validity checking is actually done!James A. Cummings,

Inc >>>

Criteria for good spreadsheet design

• Accuracy– testing– Data entry controls to limit errors

• Clarity– Easily understood by

• creator• other users

• Flexibility– Easily adapted– Remains valid

Conceptual Model for Worksheet Layout

• Input - Process - Output

• Clearly separate Input from Output

• Clearly specify Assumptions

• To be more specific …………………...

Desirable to have separate areas for:

• Identification Area• Input Area • Assumptions / Definitions / Formulas• Work Area• Output Area• Macros

(may not have them all in every sheet.) AMORT_TABLE.XLS >>

Tips• Break lengthy formulas into parts

– Easily hidden later

• Use Functions Rather than Formulas• Use Labels, Shading, Lines, Color

– anything to enhance readability

• But don’t confuse– Form over Function– Aesthetics over Accuracy

Cummings (2) >>>

Tips• Clearly specify units of measure

• No Numbers In Formulas– All placed in separate cells and referenced

• Annotate Often

• Document (i.e. Write It Down)– Assumptions– Formulas

No_5 template >>>>>

Tips• Get familiar with the Auditing Toolbar

– precedents– dependents– Trace Error Auditing Toolbar >>>>>

Testing• Accuracy of Worksheet

– test with simple and predictable data

• Full range of values

• Independent Verification– Another set of eyes– A known test problem

• Ad Hoc Testing - Whenever using a spreadsheet– The ‘eyeball’ test