1. What is Histogram ?
When creating a histogram, “a range of data is divided into smaller sections having a uniform span,and the number of data contained in each section (the number of occurrences) is counted to develop a frequency distribution table.”
Then, “a graph is formed from this table by using vertical bars, each having the height proportional to the number of occurrences in each section.”
2. When is it used and what results will be obtained?
A histogram is mainly used to analyze a process by examining the location of the mean value in the graph or degree of variations, to find a problem point that needs to be improved.
Its other applications are listed in the table below.
Method
Usage
- Used to assess the actual conditions.
- Used to analyze a process to identify a problem point that needs to be improved by finding the location of the mean value or degree of variations in the graph.
- Used to examine that the target quality is maintained throughout the process.
- Others [Used during phases to monitor the situation, analyze causes, and review effectiveness of an action.]
Result
•Can identify the location of the mean (central) value or degree of variations.
•Can find out the scope of a defect by inserting standard values.
•Can identify the condition of distribution (e.g., whether there is an isolated, extreme value).
