Bar Graphs
Many questions and investigations in biology call for a comparison of populations. For example: Are the spines on fish in one lake without predators shorter than the spines on fish in another lake with predators? Another might be: Are the leaves of ivy grown in the sun different from the leaves of ivy grown in the shade? If the variables are measured variables, then the best graph to represent the data is probably a bar graph of the means of the two samples with standard error indicated.
In Figure 1, the sample standard error bar (also known as the sample error of the sample mean) is a notation at the top of each shaded bar that shows the sample standard error (SE, in this case, ±1). Most of the time, bar graphs should include standard error rather than standard deviation. The standard error bars provide more information about how different the two means may be from each other. Sample standard error bars are not particularly easy to plot on a graph, however.
A variant of a bar graph is called a histogram. A histogram can be made for numeric data by first grouping or "binning," the variable plotted on the x-axis into intervals of equal width. The "bins" may be integers or ranges of numbers. Note that in a histogram, there is no space between the bars.
People selecting M&Ms as favorite candy
