10.3+Bar+Graphs

Section 10.3 - Bar Graphs
Bar graphs are very similar to line graphs. Instead of connecting points with lines, bars are colored in below the points. Much like different colored lines being used for different data, the color of the bar also typically represents different categories of data, or different things being measured.


 * Traditional Bar Graphs**



Notice in the bar graph above that it is very similar to the line graph, with numbers on the left axis and categories on the bottom axis. The big difference is that the categories do not represent time, such as years or months. Instead, they are distinct categories, regions of the brain in this case.

To read a bar graph, look over to the left axis and guess the height of the bar using that scale.



This example shows that the axes can also be switched, though this is not common. In this example, different colors represent different things being measured by the same scale. It is one way to show more data in a cramped graph, but there are others.

Typical questions that are asked using bar graphs:
 * Which quarter had the highest sales for product X?
 * How much more did Product Z earn in Quarter 1 than Product Y?


 * Strengths of Bar Graphs: **

Best option for comparing different categories. Easy to show comparison of the same category over time (such as last years sales compared to this years).


 * Weaknesses of Bar Graphs: **

Not very precise. Can't show a lot of data before it gets too confusing.


 * Histograms**

Histograms are a kind of bar graph. They look like bar graphs, but if you look at the categories on the bottom axis, you will see that the categories are actually ranges. If there was a bar for each $1000 of salary, there would be nearly 100 bars in the same graph, which would make it difficult to find the info you want. Instead, by grouping the bars into ranges, you can minimize the number of bars. Of course, you do lose some of the specifics, but you can still get the general picture.




 * Pictographs**

Pictographs are also a form of bar graph (with the axes switched in this case), using pictures to show the count rather than the length of the bar. In this case, a key will tell you how much each symbol or picture represents. This kind of bar graph is very useful for seeing quick comparisons between the categories, but the exact amounts are a bit harder to figure.




 * Chapter Ten Practice Problems**

**Where to from here?**
10.1 Tables 10.2 Line Graphs 10.3 Bar Graphs

10.5 Circle Graphs Chapter Ten Summary Chapter Ten Homework