Tuesday, November 13, 2012

Histogram Mode

Introduction to histogram mode

Definition: Histogram is a graphical representation showing a visual impression of  distribution of data. A Histogram consists of tabular frequencies shown as a adjacent rectangle without any intervals between the size equal to frequency of interval. This is in form of rectangles with class intervals on horizontal x - axis and corresponding frequencies at heights on y -axis.

The height of rectangle represents the frequency of interval. Frequency is divided by width of interval, and the total area of histogram is equal to the number of data.

Mode

Mode is a value that occurs most in a data set, sample data is called Scores, and sample mode is called modal score.

For example: Sample data [1, 1, 2, 2, 2, 2, 3, 5, 6] Mean = 2.

Points to Remember while Carving a Histogram

1. Frequency distribution should be always in Exclusive form.

2.Scale chosen should be appropriate, without any parameters.

3. There should not be any gap between two intervals, or adjacent rectangles.

Graphical Representation of Histogram

Example 1: A histogram showing salary v/s number of Employees

Data for the given Histogram:

X-axis represents salary (in thousands), which ranges from 0 to 87

Y- axis represents the number of employees ranging from 0 - 600 in an interval of 100.

Salary ( in Thousand)    Number of Employees
0 - 10    50
11 - 21    300
22 - 32    250
33 - 43    400
44 - 54    550
55 - 65    450
66 - 76    250
77 - 87    350
88 +    100



How to Find out Value of Mode in a Histogram

The value of Mode in a Histogram is equal to the the tallest vertical bar in a Histogram. Value which occurs most for a variable in a given data set  has highest frequency,  thus when represented in a Histogram depicts the tallest bar.

Taking the previous example of Salary v/s Number of employees:

The tallest vertical bar represents that there are highest number of employees earning salary between 44 - 54 (Thousands), so the Mode for given Histogram is 44 -54 in x-axis that has some 550 employees.I like to share this probability examples with you all through my article.

Points to Remember for Mode Value:

1. Mode can be more than one value for a given Histogram , in this case data is called multi modal.

2. There can be no mode for a given Histogram if all data occur for same number of times.

Mode value depends on the data set provided for making a  frequency distributed Histogram.

Conclusion: Histogram Mode

Histogram mode:

The highest bar in a Histogram has the highest frequency value, respective class width is called Modal value of Histogram.

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