### Chap 16 Data Handling: Histograms - How does it look like?

Key questions:
1. What is a Histogram?
2. How different is it from a Bar Chart?

1. What is a Histogram?

Frequency Table and Histogram

source: http://quarknet.fnal.gov/toolkits/new/histograms.html

2. How different is it from a Bar Chart?
source: courtesy of Ms Loh KY

1. 2.How is a histogram different from a bar chart?

-The width of each bar in a bar chart must be the same but the width of a bar in the histogram need not be the same.

-The area in a histogram represents the data but the height is used to represent data in a bar graph

-There must be gaps between the bars in the bar chart but no gaps are needed to be between bars in a histogram

2. 2. How different is it from a Bar Chart?

- In a Histogram, the area of the histogram is the amount of data. In a Bar Chart, the height of the bar chart is the amount of data.

- In a Histogram, the width of the histogram can be different. In a Bar Chart, the width of it must be the same.

- In a Histogram, there are no gaps in between the bars. In a Bar Chart, there are gaps between the bars.

3. 2. There are no gaps between the bars and the histogram is made up of vertical and horizontal axis. The verticle axis is always the "Frequency" and the horizontal axis is a series of numbers, either discrete or range. The numbers run in ascending order. We would usually be asked to find out the trend of a histogram, and be asked to compare the bar graph.

4. 2. There are no spaces between the bars of a histogram, but there are spaces between the bars of a bar graph.

Normally, we would be asked to find the trend of the histogram, whereas, we would be asked to compare for the bar graph.
The vertical axis of a histogram is always "Frequency", but for the bar graph, it could be anything.

The horizontal axis of the histogram is a series of numbers - either discrete (i.e. 2, 3, 4, ...) or range (of equal class intervals) (i.e. 20<x<=30, 30<x<40), but for the bar graph, it could be anything.

The width of the bars of a histogram could be of different sizes, whereas, the bars of the bar graph must be of the same size.