Data Visualization? What´s That?
Data visualization is simply presenting data to an end-user.
The presenter of the data and the end-user might be the same person, but in many, if not most, cases they are not. When you are presenting data by other means than the spoken word, you are using data visualization of some sort.
Data visualization is all about communication.
When we communicate with each other with spoken words, we do it through a language we have learned, either as a native speaker or you have, like me, learned a language – in this case English. The language of words helps us communicate with each other, and so we agree that some words and expressions have somewhat to strong to very strong positive or negative charges, while some are neutral. We can agree that “headache” has a negative charge, but “summer breeze” sounds more pleasant. All words have a value though.
But what if I tell you “87”? What charge does this number have? Would it be positive or negative? What about “26%”?
The number itself carries no meaning, unless we give it a value. For example, my grandfather was 87 years old when he died, and so 87 gets an emotional value to me in this sentence, and I remember old memories of my late grandfather. Or our sales decreased by 26% versus last year, which then is negative news for us.
Most of us are well-trained in the language of the spoken word but few of us master the language of numbers. Data visualization is the science of communication with the language of numbers.
When communicating each other and presenting data through data visualization, there are five tools as our disposal:
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You should use tables when
- You need to look up specific or precise values
- You want to compare individual values
- There are several different units of measure
Tables do not need to consist of numbers, the individual values can be text, or a combination of both.
You should use tables when you want to show or highlight:
- Evolution over time
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Remember that you don´t have to use a table or a graph just for the sake of it. As mentioned above, there are other tools for data visualization and if you can communicate your message clearly with just a sentence, use just one sentence. For example, in the first example above, if your end-user is only interested in the revenues figures current quarter vs last quarter, then the sole sentence “Revenues increased by 10.3% from $214 last quarter to $236 this quarter” is enough and there is no need to use a table or a graph. Remember to keep it simple.
If values are found in geographical locations, then maps are sometimes used to show spatial relationships.
Diagrams show flows or processes. See the example below from Microsoft Dev Center website.