How to plot a histogram?

To plot a histogram, put your intervals on your x-axis and the frequencies for each interval on the y-axis. Join together the intervals on the x-axis in rectangles, similar to how you would for a bar chart. The height of the bars should correspond with the frequency for that interval on the y-axis.

Expert Answers

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A histogram is similar to a bar chart, but when making a histogram, you group numbers in ranges to show the distributions of particular frequencies. For example, you could use a histogram to depict how many students of particular heights are present in a certain college class.

Before you start plotting your histogram, you need to look closely at your data to identify trends. To do this most effectively, you should use a frequency distribution table. Make a T just like you would for a T Chart. Then, on the left side, write some intervals of data. For example, if you were assessing the height of students in a class, your first interval might be 5’0 to 5’2. Then, look at how many students in the class have a height that falls into that range. If you had 5 students, for example, you would write 5 in the right column. 5 would then be called your frequency for this interval.

Once you have organized all of your data into frequencies like this, you can start making your histogram. First, write a title, to state what data you will be describing in the histogram. Then, draw a vertical line for your y-axis and a horizontal line for your x-axis and label them based on what variables they will measure.

On the y-axis will be the frequencies, so the axis should go up to the highest frequency. For example, if 9 people fell into the interval of 5’3–5’4 and that was your highest number of people in one height group, 9 would be your highest number on the y-axis. On the x-axis, you should draw equally wide rectangles to represent your interval groups, also called “bins.” For example, you would label all of the heights at the bottom of the graph and then draw a rectangle between 5’0 and 5’2 to show that this was one of your intervals. The height of the rectangle should be as tall as the corresponding frequency on the y-axis. So if you had 5 students in this interval, the height of the rectangle should go up to 5. All of your intervals should be equally spaced to help your viewer easily interpret your data.

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