Spreadsheet - Integrity
Spreadsheets | Application software
Overview | Compare with
original | Audited formulae | Check
totals | Sorting | Data
Interpretation
Spreadsheets are a valuable tool for manipulating numbers.
Unfortunately they can also hide complexities and errors.
This page deals with the integrity of the spreadsheet.
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- Use small numbers to check formulae
- Ability to make wrong assumptions when formulae are incorrect
- Check for dependencies. ie. You can use an audit feature in MS-Excel to check which
cells are required to compute a formulae (this may include cells from other worksheets or
other workbooks!)
Check totals were commonly used in manual systems. This is where the data is totalled
manually (both the number of entries and the total of the entries) and compared to the
actual figures produced by the computer.
Audit totals may be achieved by adding across totals are compared to the adding down
totals.
Common problems occurs when sorting a spreadsheet.
- Often a block is highlighted and sorted. Unfortunately data to the right (or left ) of
the block may be missed since the screen only has a limited size. So in sorting the
spreadsheet dependant data on the same row may not be.
- The sort is based on the ASCII codes so when labels are sorted into ascending order A-Z
is sorted before a-z. Watch out for spaces (eg. used to separate rows). They will float to
the top of a sorted list.
The spreadsheet may be;
- Based on assumptions.
- There are documented cases where companies have been forced to close due to incorrect
formulae.(eg. An inflation rate of 10%)
- A simulation of events, and may not take into account "real" problems that may
occur
- Since you can manipulate the figures easily, it is easy to lose sight of the fact that
the figures may not now represent a real situation.
eg. A machine may have a limit to the number of products it can produce
- Separated from external factors, such as, employee issues
- In manipulating the numbers external things such as employees may not be considered.
eg. more pay giving higher productivity!
eg. a teaching load of 2 hours may be different if you teach 10 students or 200 students.