A Gentle Introduction to Data Cleaning

Curriculum

5 Sections
17 Lessons
Lifetime

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Introduction
In this section, learn about the “horror stories” of where data errors in spreadsheets have led to real consequences and how you can avoid them yourself.
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- 1.1
  Course Outline
Section 1: Nuts and chewing gum
In this section, you’ll gain practical knowledge of common formatting and layout features of spreadsheets and some ideas about how to present your raw data to others so they will love you!
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Section 2: The Invisible Man is in your spreadsheet, messing with your data
In this section, you’ll learn how even characters which you cannot see can cause havoc in data analysis. The section will teach you to ghostbust white space and other non-printable characters such as carriage returns, spaces and tabs. Once you have removed them, you can get on with your analysis in peace.
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Section 3: Your data is a witch’s brew
Three is not a number. Nor is a million. At least not when they are typed in as text in a cell in a spreadsheet. Your spreadsheet is pedantic and needs everything to be precise and consistent. Read on to learn more.
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Section 4: Did you bring the wrong suitcase (again)?
All our spreadsheet wants from us is each cell of data to be organised and neatly packed. In this section, you will analyse data to highlight problems in the way it has been structured so as to avoid them in your own work with data.
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Introduction

All our spreadsheet wants from us is each cell of data to be organised like a briefcase of money ready to be deposited by an investment banker into an offshore tax haven:

*Image by Hair in the Gate. License unspecified*

It has one type of item, arranged in a perfect, predictable way, in standard units. It probably even smells nice. The spreadsheet is happy with this situation, and will reward us by counting, sorting, charting and so on. However, what we often give to our spreadsheet is more like a toddler’s choice of essential items to take on a day out to the coast:

*Image by Science Education Resource Centre. License CC-NC-SA 3.0.*

This sort of soft toy chaos will make our spreadsheet punish us. Lots of different items, with different characteristics and features, all jammed into the same tiny space. What can we do to sort out this mess?

By the end of this section, you will have: