# Histogram | Types of Histogram Chart | What is Histogram in 7 QC Tools?

## What is Histogram in 7 QC Tools?

→**Histogram**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

**.**

→ The data should be variable data, i.e., measured on a continuous scale. ( eg. weight, time, temperature, dimensions, speed, etc.)

→ It is a very good tool of The Basic Seven QC Tools.

### ➤ Key Concept of Histogram in 7 QC Tools:

#### ➥ The Key Concept are:

- Data always have a variation
- Variation has Pattern
- Patterns can be seen easily when summarized pictorially

## Seven Simple Steps for construction of Histogram:

### ➤ Seven Steps are:

- Collect and record the data Points
- Compute the Range
- Determine the numbers of intervals
- Determine the interval width
- Summarize the data
- Construct the Graph
- Analyze the pattern of the chart

#### ➥ Step 1. Collect and Record data:

→ For better analysis and forecasting of process collect at least 100 data points.

#### ➥ Step 2. Compute the Range:

→ Smallest Value = 204

→ Range of Values = 442-204 = 238

#### ➥ Step 3. Determine the No. of intervals required:

→ This step is for determining the no. of intervals required to construct Histogram.

#### ➥ Step 4. Determine the interval width:

→ Step 4 is for determining the width of intervals to construct.

#### ➥ Step 5. Summarize the data:

→ 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

**Histogram.**

#### ➥ Step 6. Construct the Graph:

→ Now we will construct the**Histogram**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)

- Process Centering.
- Process Variation.
**Histogram**Shape.- Process Comparison with the specification (Process Capability).

## Types of Histogram based on Pattern in 7 QC Tools:

### ➤ Various types of Histogram patterns are:

#### ➥ [A] Normal Distribution:

→ Bell Shaped Curve

→ A peak in the middle

→ A peak in the middle

#### ➥ [B] Skewed Distribution:

→ A peak is off center either right or left

→ Analysis of very pure product is skewed i.e. product cannot be more than 100%.

→ The range is not set properly for process

→ Analysis of very pure product is skewed i.e. product cannot be more than 100%.

→ The range is not set properly for process

#### ➥ [C] Double-Peaked / Bi-modal:

→ Two Bell Shaped distributions.

→ Maybe a combination of two processes or two shift’s data.

→ Maybe a combination of two processes or two shift’s data.

#### ➥ [D] Multi Peaked / Multi-modal:

→ Maybe data of several processes are plotted on the same graph.

→ Range selection is not proper.

→ Range selection is not proper.

#### ➥ [E] Edge Peaked:

→ Borderline doubt for inspection and take it as ok.

→ Instrument error.

→ 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

→ Confirms measurements to Specification

→ Excellent problem forecasting tool in process

→ Assist to decision making in the ongoing process

→ 100% of Incoming inspection and screening of mixed parts

## Benefits of Histogram in 7 QC Tools:

→ Summarize Large dataset Graphically

→ Excellent problem forecasting tool in process

→ Assist to decision making in the ongoing process

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## 2 Comments

Very well explained. @Nikunjbhoraniya.

ReplyDeleteThank you for your valuable feedback it will motivate us

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