Source: Soccerball, Public Domain http://openclipart.org/detail/167872/soccerball-noshadow-by-rduris, Baseball, Public Domain http://openclipart.org/detail/167870/baseball-noshadow-by-rduris Basketball, Public Domain http://openclipart.org/detail/167867/basketball-noshadow-by-rduris Graphs created by Jonathan O
This tutorial is going to teach you about pictographs. Pictographs are plots that show up in newspapers a lot because they're very visually appealing. What they will do is they'll use pictures instead of dots or bends.
So suppose that a class of 17 students was ask their favorite sport. One student might have drawn this graph to illustrate the results. The three soccer balls meant that three students said that soccer was their favorite sport. The five baseballs means that 5 students said baseball. And the nine basketballs means that nine students said basketball. This is a completely valid graph. It's very analogous to a dot plot, except we're using pictures instead of dots.
One student might have done, this. So another student might have created this dot plot. Notice, this looks a little funny because there's half of a soccer ball, half of a baseball here, and half of a basketball here. But notice, this student went on to say that every basketball, soccer ball, or baseball actually counts as two students.
So this is one ball, which is two students. And another half a ball, which is half of two more students. That makes three students, which is what the other students pictograph look like. This would be five students saying baseball and nine students saying basketball. This is the same as the data that was presented by the other student.
And a pictograph is going to use pictures instead of the scale or dots. And they'll often appear in the newspaper because they are so pleasing to the eye. The only problem is sometimes they can be misleading. Let's look at an example.
So in this figure, the USA had the most and Russia had the next most. But if you take a look a little closer, this is far and away higher than 1000, this is nearly 2000. And so it's not really clear what one metal icon actually means in terms of relative size. What we see is that if you divide the 1975 by six metal icons, one metal icon actually counts for 329 medals for the USA, but only 200 metals for Russia. In fact, none of these are very consistent.
What we should have done is chosen a metal icon to represent a certain number of medals and then just extended the ribbon out that far. A better looking pictograph would be something like this. I've chosen the metal icon to be 100 metals and the results when we draw out all metals will be rounded to the nearest 100. So I've lined up 20 medals for the USA because the nearest 100 would be 2000.
Russia then would have half as many metal icons to represent their 999 medals. This shows much more accurately how many more Olympic medals the USA has then the other countries. And so to recap, pictographs will use graphics instead of scales or dots to display differences in a distribution. They are legitimate graphs and they're not used too much outside of newspapers and magazines, because they are so visually appealing, they show up in these a lot.
You do need to take care though, to make sure that they're not misleading. You want your pictures to actually represent the same amount in each category. And you don't want to visually distort the picture either. So we talked about pictographs in this tutorial. Good luck and we'll see you next time.
A graphical display that uses pictures of physical objects rather than dots or bars to indicate relative size of numbers.