Visualization of any concept does help understand it better. But when playing with large data sets, I think it is necessary to also understand the relationships between the various parameters of the data before plotting them out on a graph. Also comparing or taking relative measure only makes sense if there is a strong logical reason behind doing so. For instance, David showed a comparison of Military Strength vs. Population chart. I am not really convinced that such a comparison makes sense. The military strength depends more on the border perimeter and area that needs to be defended than just the population.
However, playing around with data can definitely be great fun. Like the graph he showed:
What rises twice a year, once in Easter and then two weeks before Christmas, has a mini peak every Monday and then flattens out over the summer?
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