Histogram
A histogram is a graphical representation of the distribution of the data. It contains tabular frequencies represented in the form of rectangles adjacent to each other. These discrete intervals are known as bins. The total area of the histogram is equal to the number of the data.
Box Plot
The Box plot is a chart that graphically represents the five most important descriptive values for a data set. It summarizes the following statistical measures:-
· Median
· Upper & lower Quartiles
· Minimum & maximum data values
Comparing histogram & box plots
® The data in a histogram is represented in the form of bars which are considered as the peaks. This helps us to interpret the data and also shows the fluctuations. Whereas in a box plot the values average one another out, causing the distribution to look roughly normal.
® A histogram is preferable over a box plot is when there is very little variance among the observed frequencies. The histogram displayed to the right shows that there is little variance across the groups of data; however, when the same data points are graphed on a box plot, the distribution looks roughly normal with a high portion of the values falling below six.
® When there is moderate variation among the observed frequencies, the histogram looks ragged and non-symmetrical due to the way the data is grouped. However, when a box plot is used to graph the same data points, the chart indicates a perfect normal distribution.
Source:-
http://en.wikipedia.org/wiki/Box_plot
http://en.wikipedia.org/wiki/Histogram
http://www.netmba.com/statistics/plot/box/
http://www.brighthub.com/office/project-management/articles/58254.aspx#
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