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Where Are You Flying?

Age 14 to 18 Challenge Level:
Some observations about these four representations:
  1. Pie charts are generally quite poor representations, as it is hard to compare angles, and there is no indication of absolute sizes.  (There may have just been 100 flights, or maybe 10 million, for example.)
    3D pie charts worse still, as segments near the back appear smaller than segments near the front, which is misleading.
    Exploded 3D pie charts are even worse, since the sizes of the segments become even harder to compare, and segments moved towards the viewer appear even bigger.  And one segment is almost completely obscured.
    The colour choices are misleading, as dark colours attract attention and can make the segment seem larger than it is, while pale colours become less obvious.
    The colour choices also make it hard to distinguish between some of the sectors: which one is Europe and which is North America, for example?  And what about Africa and Oceania?
    In the content of the article, the headline talks about "tourist destinations", while we only know about flight destinations, not people's reasons for travelling.  Also, people visiting New Zealand do not fly directly there, so it is likely that their flights will be recorded as going to Asia (where they will then change for a connecting flight).
  2. It is very difficult to compare the sizes of these aeroplanes, and the ones in South America and Oceania are almost invisible.
    It is unclear whether the areas or lengths of the planes are to be compared.
    There is also no indication of absolute size.
    The caption talks about popularity of destinations, but we don't know how many people flew to these destinations, only the number of flights.
    It is not quite clear why there is a plane over the UK, but we could probably make a reasonable guess.
  3. It is clear what each disc refers to.
    All of the discs have the same colour, which makes it easy to compare them.
    It is clear that the number of flights to Europe is the greatest by some margin, while Domestic, Asia and North America have approximately equal numbers of flights.
    The caption is meaningful and accurate; that the discs show the number of flights to each destination is implicit.
    However, there is no scale indicated, so we do not know whether the discs are to be compared according to their radius or area, and there is no indication of absolute size.
    The discs for Souther America and Oceania are almost invisible, which is somewhat unhelpful.
  4. The graph has a scale, which means that numbers can be read from the graph.
    The caption is accurate.
    Each bar has the same colouring making them easy to compare.
    The graph starts at 1, so the graph is not misleading through use of a strange starting point.
    However, the graph is on a "log scale" which makes it seem at a first glance that there is not that much difference between the different destinations, even though Europe has over 100 times more flights than Oceania.
    It is also somewhat difficult to read an actual number from the scale; for example, it looks as though there were about 600 000 flights to Europe, whereas there were actually less than 400 000 flights.
For the data itself, we might ask a variety of questions, for example:
  • How reliable are these figures?
  • How do the number of passengers relate to the number of flights?  Would it have been more useful to have passenger numbers instead?
  • Very few people fly directly to Oceania, and direct flights only started very recently.  So what are these 1442 flights?
  • Related to the previous point, if people fly to somewhere far away and they take a connecting flight, what is the destination recorded as?  So what does the data actually tell us?
  • If we want to know where people fly, wouldn't it be simpler just to ask them (thinking about representation 1)?