Thursday, 26 December 2013

How to Make Bar Graphs

Sample Bar Graphs Making Your Own Bar Graphs

Edited by Star*star, IngeborgK, Teresa, Daniel Bauwens and 6 others

Bar graphs are a method of comparing categories, consisting of either vertical or horizontal rectangular bars whose lengths are proportional to amounts or quantities.

The base of bar graph of categories, or groups, may often be in any order, where order does not matter. However, chronological order is common for a certain time period, for example: by days of the week, by months of a year, or by years or other periods, measures of time.

EditSample Bar Graphs

Sample Horizontal Bar Graph

Sample Vertical Bar Graph

Sample Stacked Bar Graph

EditMaking Your Own Bar Graphs

1
Collect or obtain data, and choose your data categories. The most simple kind of bar chart displays how one measurement corresponds in certain categories. (Another use of rectangular bars on a graph is called a "histogram", not "bar graph", to display a continuous range of data in increasing or decreasing value in a list of equally divided range segments to show how these compare.)
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2
Choose which set of data is the base of your bars. Bar charts are often drawn when one set of data is expressed as a set of categories (which can be periods of time), in which case this set will be the base. The other axis will be values (sales, costs, grades, scores, production amounts, other quantities, etc) for the base categories, groups or periods. (If neither set includes any range, category, group or period, you should consider using a line chart instead of bar graph or histogram.)
3
Decide whether your bars should touch. Bars on a histogram can touch because their ranges share a border. This type would not be called a "bar graph" but a "histogram", showing a distribution over the chosen range.
- A histogram with touching bars might have ranges 0 - 5, 5 - 10, 10 - 15 or perhaps fractions of a minute, or an hour, etc. where the data is over a continuous range.
- A bar chart with bars that do not touch might have ranges 0 - 4, 5 - 9, 10 - 14 or January, February, March where the data is not continuous.
  
  ~~ The bar graph is not a distribution over a range, but only a visual comparison of categories, groups, or periods.
4
Draw the bottom axis and mark where the bars will be. Divide the number of squares (convenient units) across the page by the number of bars you need to draw to find the width of each bar. If this gives a fraction, round down to the nearest whole number. If the bars do not touch, choose a convenient space and leave this blank between the pairs of bars, often from an appropriate beginning point, such as January, or a certain year.
5
Label the bottom axis. If the bars touch, as in a distribution, label where they meet with the boundary they share. If the bars are separate, label each in the centre with it's name, value, or range.
6
Draw and label the side axis. Divide the highest value of all the bars by the number of squares left above the bottom axis to find what each square represents. If this is a fraction, round up to the nearest whole number. Label the point where the axes meet as 0. Each square above 0 increases by the calculated amount until the value is equal to or greater than the largest vertical bar.
7
Draw your bars. Extend the base you have marked on the bottom axis to the horizontal line labelled with the value of that bar. If the value falls between two lines, approximate where the correct value would lie. Notice that bars are normally separated (not continuous), as they are comparing the value of different but comparable events, unless this is a distribution (histogram).
8
Label the axes with what they each represent and add a title for the graph.
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Edit Tips

Bar charts can also be drawn sideways by exchanging the vertical and horizontal axes.
More complicated bar charts can be drawn if each range corresponds to two or more values. In this case, divide the space each bar would occupy into several touching bars. Go through each set of values in turn using the leftmost unfilled bar, and colour each completed set a different colour.