This is the second (and final) article looking at key aspects of datasets. Having previously covered relevance, accuracy, and precision, here we will consider consistency, completeness and size.

Consistency

On the 23rd of September 1999, NASA's Mars Climate Orbiter entered the Martian atmosphere and burned up. This $125 million dollar mistake was down to inconsistent use of units between two different pieces of software…

You may associate animated GIFs with questionable website design from the mid-nineties or modern internet meme culture. In terms of data visualization, when comparing to an interactive JavaScript application it's easy to think of an animated GIF as being a vestigial organ of the world wide web. Beyond, perhaps, allowing the user to (re)start the animation (using a little JavaScript) the animated GIF is, essentially, inflexible…

Whether compiling your own dataset or using somebody else's, there's huge potential for wasting both time and money if the data isn't fit for purpose. This is the first article in a two-part series taking a (largely qualitative) look at evaluating the usefulness of datasets. In this part I will cover relevance, accuracy and precision; part two will cover consistency, completeness and size.

Relevance

It is…

Hopefully you're familiar with the standard scatterplot - a selection of points where each x coordinate is determined by one variable and each y coordinate by another. Below is a simple example, showing the number of countries winning one or more medals versus the total number of medals awarded for all Summer Olympic Games from Athens in 1896 to London in 2012. The data was assembled from Wikipedia's articles on Olympic…

While writing my recent articles on slopegraphs I became intrigued by the unusual shapes of some of the population curves of the countries and decided to read around the subject a bit. It was through this that I stumbled across a Wikipedia article on the Demographics of Japan. A chart concerning birth rates and death rates in the country piqued my curiosity:

The big picture is one of (generally) declining birth rates…