What a review consists of
In a large spreadsheet, where there may be tens of thousands of cells containing formulas and thousands of distinct formulas, it would take a long time for a reviewer to manually test and validate every cell. The impracticalities of cost and time would make it inevitable that corners will be cut. Instead, it is helpful to target the most critical areas and outputs.
The guide focuses on five main review stages:
Initial review: checking the big-picture elements to get an initial impression of the state of the workbook and prepare for later stages of review.
Structural review: checking that the spreadsheet is well laid out and includes appropriate checks.
Data review: checking the validity of the input data used in the spreadsheet.
Analytical review: checking if the spreadsheet’s output looks reasonable at a holistic level.
Detailed review: checking the spreadsheet at a more detailed level, including at the individual formula level.
Questions to consider before construction starts
An essential consideration is whether the appropriate package is being used by someone with sufficient competence – and, indeed, whether a spreadsheet is the appropriate tool in the first place. Some of the core areas to consider include:
- What is the purpose of the spreadsheet?
- What level of risk is associated with the spreadsheet?
- How competent is the author?
- Has the spreadsheet been subject to any earlier review?
- What is the life cycle of the spreadsheet?
- What construction controls have been used?
- Should passwords be required?
Post-review activities and useful functionality
The review does not end when the last formula has been checked, but rather when the findings of the review have been documented, communicated to the appropriate people, and changes have been implemented. It could also lead to another review.
The guide includes a synopsis of post-review activities and presents some useful Excel functionality that can support a detailed review.
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How to review a spreadsheet
When a spreadsheet is being used to provide the numbers that form the basis of a significant decision, it is reasonable to expect that the data, logic and results are reviewed for accuracy.
This guide follows our previously published work:
ICAEW Thought Leadership
Twenty principles for good spreadsheet practice
Twenty principles for good spreadsheet practice aims to reduce the amount of time wasted and the number of errors caused as a result of how spreadsheets are used.
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Spreadsheet competency framework
The Spreadsheet competency framework is a structure for assessing ability and proficiency when using spreadsheets to help get the right person with the right skills in the right role.
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The Financial modelling code
The Financial modelling code provides a set of principles for robust modelling. Each section of the code addresses a particular element of constructing a model and explains its goals.
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