## What is a Scatter Diagram in 7 QC Tools?

→ Scatter Diagram is used to study and identify the possible relationship between two variables.→ It is also used to validate the relationship between cause and effect and it is also known as the validation tool.

→ Scatter Chart in

__7 QC Tools__is a graph in which the values of two variables are plotted along two axes of the graph, the pattern of the resulting points will say the correlation.

→ We use this chart to find out the relation between cause and effect by using a cause and effect diagram.

→ This tool is commonly used in the

__analyze phase__in the

__Six Sigma Methodology__.

### Scatter Plot Examples

→ Refer below to the relations of two variables that we can find in our real life.- Weight and Height of a Man.
- Hardness and carbon content in the product.
- Visual Inspection mistakes and Illumination levels.
- Child’s height and Father’s height.
- Curing Temperature and Curing Time.
- Advertising and sales.

### What is a scatter diagram used for?

- It is used for the validation of two different variable
- It is also used for checking the trend with respect to time
- The Scatter_diagram is used to confirm a hypothesis testing between two variables.

## How to draw a Scatter Diagram?

→ Refer to the four steps for Making a Scatter_Graph.

- Data Collection
- Choose Independent and Dependent variables.
- Construct the Graph and add the titles & trend line.
- Interpret the Graph

#### Step 1. Data Collection:

→ Now we are taking one example to understand how to make a chart?→ In this example, we are taking 50 readings of different curing temperatures on different curing times for a product manufactured on the thermosetting press. we want to find out the relationship between curing time and curing temperature.

→ We have to find if any correlation is present or not between curing temperature and curing time.

→ If we have more data samples then it will give a more precise result.

#### Step 2. Choose Independent and Dependent Variables:

→ The dependent variable is usually plotted along the vertical axis i.e. in Y-axis and it is called a measured parameter.→ The independent variable is usually plotted along the horizontal axis i.e. in X-axis and it is called a control parameter.

→ In this case, we are taking heating temperature as an independent variable on the x-axis, and curing time is dependent on heating temp. so we mentioned it on the y-axis.

#### Step 3. Construct the Graph and add the titles & trend line:

→ Now based on recorded data construct a graph and add a suitable title, horizontal axis name, vertical axis name, and make trend line.#### Step 4. Interpret the Graph

→ We will interpret the chart based on the trend line.### Types of Correlation in Scatter Diagram in 7 QC Tools:

→ There are many different types of correlation found between the Independent and Dependent variables which are mentioned below with pictorial representation.→ Mainly three relations available between two variables we can say that Strong, Moderate, and No Relation.

→ A strong positive correlation means it is a clearly visible upward trend from left to right, a strong negative correlation means it is a clearly visible downward trend from left to right.

→ eg. In positive relation, as the value of x increases, the value of y will also increase we can say that the slope of the straight line drawn along the data points will go up and the pattern will resemble the straight line.

→ For example, in the summer season the temperature increase, icecream sales will also increase.

→ A negative correlation, as the value of x increases, the value of y will decrease and the slope of a straight line drawn along the data points will go down.

→ For example, in the summer season the temperature increase, the sales of winter coats decrease.

→ A weak correlation means it is less clear that the relationship is either positive or negative?

→ No correlation means neither positive nor negative relation and indicates the independent variable does not affect the dependent variable.

### What are the 3 types of scatter plots?

→ There are main three types mentioned below.

- Positive
- Negative
- Neutral

⇢ (1) Strong Positive

⇢ (2) Moderate Positive

⇢ (3) Weak Positive

⇢ (4). Strong Negative

⇢ (5). Moderate Negative

⇢ (6). Weak Negative

⇢ (7). Random Pattern

### Benefits of Scatter Diagram:

→ It is beneficial to confirm a hypothesis (assumption) between two variables that are related or not.→ Provide both visual and statistical means to test the strength of a potential relationship.

→ It is a very good validation tool.

→ Used for proving the relation between

__cause and effect__.

→ Plotting the diagram is relatively simple.

### Limitation of Scatter Plot:

→ It does not show you the quantitative measure of the relationship between the variable.→ This chart does not show you the relationship for more than two variables at a time.

👉 See Also:

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