Lesson 6.8

Scatter Plots

In Algebra, lines are perfect. In the real world, data is messy. Scatter plots help us make sense of the mess.

Introduction

A scatter plot is just a graph with a bunch of dots. Each dot represents a single data point. We look at the "cloud" of dots to see if there is a pattern.

Past Knowledge

Lesson 4.1 (Coordinate Plane). You know how to plot .

Today's Goal

Identify Positive, Negative, and No Correlation.

Future Success

This is the foundation of **Statistics**. Finding trends in data is one of the most valuable skills in the modern world.

Key Concepts

Types of Correlation

Positive

Both go UP together.

Negative

One UP, one DOWN.

None

Total chaos.

Worked Examples

Example 1: The More, The More

Positive

Scenario: Height vs Shoe Size

As people get taller, their feet usually get bigger.

Trend:

The dots go UP and to the RIGHT. This is a Positive Correlation.

Example 2: The More, The Less

Negative

Scenario: Car Age vs Value

As a car gets older (Age goes UP), its price goes DOWN.

Trend:

The dots go DOWN and to the RIGHT. This is a Negative Correlation.

Example 3: No Relationship

None

Scenario: IQ vs Shoe Size

Being smart has nothing to do with how big your feet are.

Trend:

The dots are scattered everywhere. There is No Correlation.

Common Pitfalls

Correlation != Causation

Just because two things move together doesn't mean one causes the other. Example: Ice cream sales and shark attacks both go up in summer. Does ice cream cause shark attacks? No! The heat causes both.

Ignoring Outliers

One weird dot doesn't ruin the trend. If almost all dots go up, it's still positive, even if there's one data point that breaks the rule.

Real-Life Applications

Marketing Analytics:

  • Companies scatter plot "Advertising Money" vs "Sales Revenue".
  • If they see a strong positive correlation, they know their ads are working.
  • If they see no correlation, they know they are wasting money on ads!

Practice Quiz

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