Spreadsheet Errors John Park
- 1. Spreadsheet ErrorsBy John Park
- 2. Some Important ConsiderationsFrequency: How common are the different types of errors? Classification: What are the different types of errors?Impact: What are the consequences of spreadsheet errors?Creation and Prevention: Why do these errors occur? Detection: How can find and correct these errors?
- 3. It Can Happen To You!Frequency of Spreadsheet Errors“Since 1995, when field audits began to use good methodologies, 88% of the 113 Spreadsheets audited in 7 studies ... have contained errors.” (Panko, 1998)
- 4. Types of ErrorsQualitative ErrorsStructural – Flaws in the design of the spreadsheetHidden - Errors that only arise during useVisible – Can be observed in the current spreadsheetTemporal – Errors that arise from the use of non-current dataQuantitative ErrorsMechanical Errors – Mistakes in typing or pointingLogic Errors – Choosing the wrong function or creating the wrong formulaOmission Errors – Misinterpreting the situation to be modeled
- 5. Small Errors Can Have A Huge ImpactCandidates for police officer jobs are told they passed the test when they failed. Reason: The spreadsheet was sorted improperly.A school loses L30,000 because its budget is underestimated. Reason: Numbers entered as text in a spreadsheet. Benefits of unbundling telecommunication services are understated by $50 M. Reason: Incorrect references in a spreadsheet formula.
- 6. Common Reasons for ErrorsLack of TimeBurnoutOverconfidenceLack of StructureInexperienceAfraid to ask for help