Data at Work: Best practices for creating effective charts and information graphics in Microsoft® Excel®

4. Data Preparation

Jacques Bertin defines his semiology of graphics as a “visual transcription of a data table.” In a perfect world, this table materializes in front of us when we need it, ready to use. In everyday reality, however, things involve more sweat and less magic. People coined the expression “data janitor” for a reason.

In a data visualization project, data extraction costs and data preparation are often overlooked, either by management that doesn’t understand the level of detail required or by data analysts making overly optimistic assumptions. This translates into many hours of data cleansing that most people don’t see. If not taken into account, these labor-intensive tasks can consume several times the resources available for a ...