Another important question is why use graphical representations? Well, there are a number of ways to answer this question. And the first way is that humans are actually visual animals. It is estimated that up to 30 percent of the cortex of the brain is devoted to vision, and we have two big pairs of eyes and we are incredibly good at extracting and processing formation that comes from our environment. So, humans are inherently visual animals, and we are very, very good at processing visual information. The second way to answer that, requires asking another question. And the question is, if not graphically what are other ways to communicate information? So here, I'm listing three main ways to communicate information. The first one is verbally, the second one is numerically, and the third one is graphically, using graphical formats. So, in order to explain a little better these three modes of communication, I want to give you an example, and this example is based on a new data set. It's a data set that describes flights leaving from New York City in 2013, and it records information about several airlines, carriers, different times of the day, and how much delay they experience on average at different times of the day. So, let me show you this information first in a table. So, this table is organized as follows: In rows, you have the carriers; in columns, you have hours of the day; and every single cell, records the average delay. Now I want you to take some time, spend some time observing this table, and ask yourself some questions. The main question is, what can you see here? What can you learn about airline delays? For instance, are there any particular hours in which the airlines tend to have higher delays or lower delays? Is there an airline that tends to have more delays than other airlines? Or does the amount of delay change considerably from one airline to another? So, spends a few seconds or even minutes reviewing this table in trying to answer these questions. Now, in this graph, I am visualizing exactly the same information that we had in the table, but now, in a graphical format. How do you read this? Every single line represents one carrier, one airline. On the x-axis, you have time during the day, and on the y-axis, you have the average delay. Now observe this graph, spend some time observing this graph and try to think about the same thing. What do I see here? What can I learn about flight delays by observing this graph? Is there any airline that stands out? Can I learn something about what time during the day there are major delays? Is there anything that is strange or weird? So, take your time. And here, I want to show you an example of communicating some of the same information verbally. I'm going to read this paragraph. The average delay increases steadily throughout the day, starting from 6:00 AM until around 9:00 PM. Much higher delays take place between 3:00 PM and 9:00 PM. And among the airlines we considered, EV and WN, experienced much steeper increases. EV experiences, in general, much higher delays than all the other airlines regardless the time of the day. So this is very different. It's a very different mode of communicating information. How does it differ? Well, one thing that stands out when I'm trying to communicate information verbally is that we are forced to process this information sequentially. That's a big, big difference. Whereas, when we are observing a chart, we are actually consuming and processing this information in a parallel fashion, all at once. We don't need to go through it sequentially, necessarily. The same in principle is true also for the table, but the problem with the table is that there is not much to see, there is not much to perceive , we have to process numbers that don't match directly, visually to some quantities. So, these are the three main modes and I think it's a good example for you to understand what is the difference between these three modes, and also why we want to visualize information, why it's good, at least in some cases, to communicate information in a graphical format.
