Histogram

Histogram

Histogram
Histogram of arrivals per minute.svg

 

Video: What is a Histogram?

 

What is a histogram?
A histogram is an accurate representation of the distribution of numerical data. It is an estimate of the probability distribution of a continuous variable (quantitative variable) and was first introduced by Karl Pearson.

 

How does a histogram differ from a bar graph? 
Histogram differs from a bar graph, in the sense that a bar graph relates two variables, but a histogram relates only one. Histograms are sometimes confused with bar charts. A histogram is used for continuous data, whereas the bins represent ranges of data, while a bar chart is a plot of categorical variables. Some authors recommend that bar charts have gaps between the rectangles to clarify the distinction.

 

Video: How a histogram is different than a bar chart?

 

How do you construct a histogram?
To construct a histogram, the first step is to "bin" (or "bucket") the range of values—that is, divide the entire range of values into a series of intervals—and then count how many values fall into each interval. The bins are usually specified as consecutive, non-overlapping intervals of a variable. The bins (intervals) must be adjacent, and are often (but are not required to be) of equal size.

 

Video: Statistics - How to make a histogram

 

Is a histogram used in quality control?
Yes, the histogram is one of the seven basic tools of quality control.

 

Video: When to Use Histograms

 

Example of a histogram

This is the data for the histogram to the right, using 500 items: 

Example histogram.png

Bin Count
−3.5 to -2.51 9
−2.5 to -1.51 32
−1.5 to -0.51 109
−0.5 to 0.49 180
0.5 to 1.49 132
1.5 to 2.49 34
2.5 to 3.49 4

 

Video: Statistics - Reading the shape of a distribution

 

What are the different patterns one can see in a histogram?
The words used to describe the patterns in a histogram are: "symmetric", "skewed left" or "right", "unimodal", "bimodal" or "multimodal".  
  • Symmetric, unimodal

  • Skewed right

  • Skewed left

...........

 

 

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Let's Review 

  1. A _________ is an accurate representation of the distribution of numerical data.
  2. A histogram is an estimate of the _________ distribution of a continuous variable (quantitative variable)
  3. Histogram differs from a bar graph, in the sense that a bar graph relates _________ variables, but a histogram relates only _________.
  4. A histogram is used for _________ data, whereas the bins represent _________ of data, while a bar chart is a plot of categorical variables.
  5. Histogram is one of the seven basic tools of _________ _________.
  6. The different patterns that can be seen in a histogram are "_________", "_________ _________ _________ " or "_________", "_________", "_________" or "_________".
  7. Histograms give a rough sense of the _________ of the underlying distribution of the data. 

 

Answer

  1. A histogram is an accurate representation of the distribution of numerical data.
  2. A histogram is an estimate of the probability distribution of a continuous variable (quantitative variable)
  3. Histogram differs from a bar graph, in the sense that a bar graph relates two variables, but a histogram relates only one.
  4. A histogram is used for continuous data, whereas the bins represent ranges of data, while a bar chart is a plot of categorical variables.
  5. Histogram is one of the seven basic tools of quality control.
  6. The different patterns that can be seen in a histogram are "symmetric", "skewed left" or "right", "unimodal", "bimodal" or "multimodal".
  7. Histograms give a rough sense of the density of the underlying distribution of the data. 

 

Test Your Knowledge

 

 

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