8.FGR.6.1 Analyze Linear Associations

Scatter Plots

This is for students that missed class on Monday, March 7. Please complete these slides to catch up on material.​

​Definitions:

Variable: A variable is a placeholder for a number we do not know yet. A variable can be anything, but it is usually represented by a letter.

Coefficient: The coefficient is the number in front of the variable.

Ex: 3x​ the coefficient is 3

Like Terms: Like terms are terms that share the same variable.

We combine like terms by adding the coefficient.

Ex: 3x and 5x are like terms and if we combine them we get

(3 + 5)x = 8x​

Subject | Subject

Some text here about the topic of discussion

​Positive Association	​Negative Association	​No Association
​Both variables are increasing.	One variable is increasing, the other is decreasing.​	There is no relationship between the variables.​

​Types of Association

Multiple Choice

What type of association does this graph have?

• positive 
• negative
• none
• all of the above

Scatter Plots can be described as linear and non-linear models. They are not perfectly linear or non-linear but they​ follow a trend.

Linear vs. Non-linear Models

​

Multiple Choice

Which scatter plot shows a linear relationship between x and y?

• Graph A
• Graph B
• Graph C
• Graph D

Correlation coefficient

Multiple Choice

Describe the correlation in the graph shown.

• Strong Negative

• Strong Positive

• Weak Negative

• Weak Positive

What is a Trend Line (Line of Best Fit)?

When data is collected, points do not form a straight line, but they may approximate to a linear relationship

A trend line is a line that is

VERY CLOSE to most of the data points.

It is used to make conjectures (predictions)

Multiple Choice

What is a trend line used for?

• To make predictions

• To make the graph look pretty

• To connect the points

First, Lets make a trend line!

- Count the number of points, make a line that best fits the data points.

TIP: Count the number of total points. Try to have the same number of points on both sides of the trend line

Multiple Choice

Which of the following lines represents the line of best fit for the scatter plot?

• A

• B

• C

• D

Multiple Choice

Which of the following lines represents the line of best fit for the scatter plot?

• A

• B

• C

• D