Management Paper – Commercial Spreadsheet Review

Simon Murphysimon.murphy@codematic.netDeveloper – Codematic Ltd

Spreadsheet background• Up to 200 Mb size• Up to 1 Million formulas• 1-10,000 unique formulas• 5-10,000 lines of VBA• £1M to 100’s of Billions in values• Often linked to other technologies

such as OLAP, ADO, COM or .net etc.• Finance, Banking and Sales and

Marketing areas

Agenda• Introduction• Scope of Review• Stages of Review

– Spreadsheet in context– File Review– Workbook Review– Sheet Summary– Inter Sheet Interactions– Cell/Block level Relationships

• Summary• Conclusion• Any Questions?

Introduction - Spreadsheet Quote

Program Manager to Steering Committee:

“We can build this system in – a large consolidation software package –, it will take 2 developers 6 months and cost half a million. Or 1 developer can do it in Excel in 10 weeks for 30 thousand.”

Introduction - Spreadsheet Definition

• 2006 - Organisational

–Spreadsheet – the product of one or more people following some sort of process to a deadline.

• 2005 - Technical

– Spreadsheet – powerful and flexible, single end user, analysis and presentation tool, optimised for speed of initial development.

Scope of Review• The review is pre-sales (i.e. ‘free’)• The aim of the review is to estimate

the time to repair, enhance, or migrate the spreadsheet.

• Totally NOT any sort of audit.• Target time is 2-4 hours.• Explicit assumption the spreadsheet

is fit for purpose currently.• Assumes no useful documentation.

Spreadsheet in Context• What is it used for?• How important is it?• How connected is it?• Is network access required?

File Review• Virus scan• Workbook file properties• Remove protection

Workbook Review - 1• Open with VBA disabled• Check any VBA code (and XLMs) for

security issues

Workbook Review – 2• Review summary

metrics

Workbook Review - 3• Run XLAnalyst for brief summary• High score may make review harder

Workbook Review - 4• Glance at unique formulas

Sheet Summary• Once sentence summary (if possible) of

what the sheet does.• Added to navigation sheet

Inter Sheet Interactions

• Data flows• Left hand are pure children/source sheets• Right hand side are unconnected (by basic formulas)

Inter Sheet Interactions

Inter Sheet Interactions

Inter Sheet Interactions

Cell/Block level Relationships

• Review named ranges

• (Free tool - Google for NameManager)

Cell/Block level Relationships• Quick value type overview

Cell/Block level Relationships• Review the actual formulas for shapes

• Finally work though a few formulas

Cell/Block level Relationships• Real world flows

Cell/Block level Relationships• Real world flows

Some Fun Formulas1. =IF(AND(AND(AND(AND('s29'!AK50=0,'s29'!

AK51=0,'s29'!AK54=0,'s29'!AK55=0)))),"N","")2. =IF(AND($E$45="a",AF9>0),AK45,IF($E$45="M"

,AK45/12*$E$9/30,IF(AND($E$45="Q",AF9>0),IF(AK50=12,AK45/4,IF(AK50=11,AK45*3/11,IF(AK50=10,AK45*2/10,0))),AK45*0)))

3. =IF(AND(I89<>0,I88=0,SUM($U$88:U88)=0),1,IF(OR(ISERROR(I89),NOT(ISNUMBER(I89))),"Error",0))

4. =+B49*(0.173076923076923)5. =+E27*SUM(D5/G5)6. =SUM('PayEx'!$U5*'PayEx (Annual) '!

$J$5)*(100%+'% Increase in x'!CH7)7. =G43*1000/G83

Last one• =E111+E118+E119+E120+E121+E

122+E123+E124+E125+E185+E186+E187+E188+E189+E190+E191+E216+E217+E218+E219+E220+E222+E223+E227+E233+E234+E240+E241+E246+E468+E469+E470+E471+E472+E475+E533+E534+E535+E536+E537+E540+E579+E580+E581-E257-E252

Summary• Brief overview of one commercial

review process• Aim to drill into a spreadsheet one

level at a time• Target is to make changes to a live

spreadsheet without introducing new errors

Conclusion• Using a few basic tools and a

structured approach it is possible to gain a reasonable understanding of a spreadsheet within commercially viable timescales.

Questions?

• simon.murphy@codematic.net– Spreadsheet consulting, reviewing,

maintaining, rescuing, migrating, add-in development etc.

• Websites– www.codematic.net– www.xlanalyst.co.uk