What is a Histogram graph in 7 QC Tools?

What is a histogram used for?

It is used for showing a large data set graphically

Problem forecasting

Study the variation in the ongoing process

Key Concept of Histogram in 7 QC Tools:

How to Make a Histogram?

Data Collection Compute the Range Determine the numbers of intervals Determine the interval width Summarize the record Construct the Graph Analyze the pattern of the chart

[01] Data Collection:

[02] Compute the Range:

[03] Determine the No. of intervals required:

[04] Determine the interval width:

[05] Summarize the record:

[06] Construct the Graph:

[07] Analyze the Graph pattern:

Examples of Histogram Graphs

Types of Histogram Patterns

Benefits of Histogram:

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Cause & Effect Diagram (Fishbone or Ishikawa) 2.(Fishbone or Ishikawa)

→ It is a type of bar chart representing the frequency distribution of the data from a process.→ Only one parameter can be used for constructing this chart.→ It is a frequency distribution tool of the Basic→ The parameter must be variable data, i.e., measured on a continuous scale. ( eg. weight, time, temperature, dimensions, speed, etc.)→ This tool is used in theof➨ The Key Concept is:⇢ Data always have a variation⇢ Variation has Pattern⇢ Patterns can be seen easily when summarized pictorially→ Seven Steps are mentioned below for making the histograph:→ For better analysis and forecasting of process collect at least 100 record points.→ Here we take an example of 150 record points for making a chart.→ Largest Value = 442→ Smallest Value = 204→ Range of Values = 442-204 = 238→ This step is for determining the no. of intervals required.→ Step 4 is for determining the width of intervals to construct.→ In Step 5 we will summarize the data as per the interval and count the frequency of data as per range value for construction of the_graph.→ Now we will construct the_graph by mentioning the Title,→ Y-axis/Vertical axis = Interval width, X-axis/Horizontal axis = Interval width,→ Graph - Trendline and Legend (if applicable).➨ Five Important Parameters in Histogram:⇢ Title⇢ Y-axis/Vertical axis = Interval width⇢ X-axis/Horizontal axis = Interval width⇢ Graph - Trendline⇢ Legend (if applicable)⇢ For a better understanding of these 5 parameters study below chart:→ Interpretation of the Graph⇢ Central Tendency⇢ Process Variation⇢ Histogram Shape(Comparison with the specification)→ Various types of Histograms based on patterns are mentioned below➨ [A] Normal Distribution:⇢ Bell Shaped Curve⇢ A peak in the middle➨ [B] Skewed Distribution:⇢ A peak is off-center either right or left⇢ Analysis of very pure products is skewed i.e. product cannot be more than 100%.⇢ The range is not set properly for operation➨ [C] Double-Peaked / Bi-modal:⇢ Two Bell Shaped distributions.⇢ Maybe a combination of records of two processes or two shifts.➨ [D] Multi Peaked / Multi-modal:⇢ Maybe readings of several processes are plotted on the same graph.⇢ Range selection is not proper.➨ [E] Edge Peaked:⇢ Borderline doubt for inspection and take it as ok.⇢ Instrument error.➨ [F] Truncated or Heart-cut:⇢ The supplier might mix apart within spec and out of spec. limit.⇢ 100% of Incoming inspection and screening of mixed parts.→ Summarize Large data set Graphically→ Confirms measurements to Specification→ Excellent problem forecasting tool in the process→ Assist to decision making in the ongoing process