This document discusses common causes of errors in spreadsheets. It identifies misunderstanding functions, incorrect data input, and hiding lines as frequent sources of errors. Specific examples are provided to illustrate each type of error, such as incorrectly using the NPV function by including current investments or inputting the wrong number that then propagates errors. The conclusion acknowledges that spreadsheet errors are easy to make but can be embarrassing and costly, so models should be carefully checked and reviewed to catch mistakes.

1. Introduction to Spreadsheet Errors Designing Financial Models that Work Melissa Ma April 5, 2010

3. Your heart starts beating uncontrollably when the error is identified by a client

6. Now everything linked to that cell is 10x the amount you wantInputting the incorrect data creates a snowball effect and creates a systematic error throughout your spreadsheet

7. Common Cause of Errors: Hiding Lines Example: You forgot you hid a line, and have now pasted it into a presentation Presentation Sheet Actual Sheet You forgot you hid the row, either delete the row OR unhide to make sure all the rows add up to the right amount Used the sum function, but the numbers don’t seem to add up?

8. Conclusion We are all human and we all make mistakes Spreadsheet errors are very common Errors are often embarrassing and very costly Errors have many sources and can stem from a variety of input and formulaic mistakes Check your spreadsheet over and over and try to prevent errors when you can!