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### Course: Algebra 1 (Eureka Math/EngageNY) > Unit 2

Lesson 14: Topic D: Lesson 19: Interpreting correlation- Bivariate relationship linearity, strength and direction
- Positive and negative associations in scatterplots
- Example: Correlation coefficient intuition
- Correlation coefficient intuition
- Correlation and causality
- Calculating correlation coefficient r
- Correlation coefficient review

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# Positive and negative associations in scatterplots

We make scatterplots to see relationships between variables. Scatterplots are really good for helping us see if two variables have positive or negative association (or no association at all).

## Problem 1: Flower height and petal length

Sam measured the height and petal length (in centimeters) of all the flowers in his garden.

Height | |||||||

Petal length |

## Problem 2: Car driver age

Data was recorded on the age of drivers and the number of car accidents per $100$ drivers in the year $2009$ . The data is shown in the scatterplot below.

## Problem 3: Shoe sizes and test scores

Dexter's class recorded data on the test grades and shoe sizes of students in the class. The data is shown in the scatterplot below.

## Want to join the conversation?

- What's the difference between a nonlinear graph and no correlation? Is a nonlinear graph basically not a straight line? (e.g.- a quadratic graph) and it's no correlation is the points are plotted "randomly," right?(36 votes)
- No corellation mean that its not positive or negative and non linear mean that its not line and dont relate(15 votes)

- is this going to help me in the real world when I'm 20(31 votes)
- Well, it might. You might need to use this to analyze your spending and saving habits. Is your money spending going up as you get older? Questions like these, graphs like such can help you with.(8 votes)

- is this going to help me in the real world when I'm 20(19 votes)
- tbh this is the one of only things in math that's actually useful in real life. we don't want stupid people misinterpreting information and spreading it.(15 votes)

- What is the difference between "no association" and "nonlinear association"? Thanks!(11 votes)
- No association means that there is no line and all the dots are scattered. Nonlinear association means that the dots are close to each other but are not in a
*line*.(10 votes)

- why is math so important in our daily life $$$(8 votes)
- How can you tell if a correlation is strong or weak?(7 votes)
- Consider its absolute value (| |). An acceptable strength criteria varies by discipline. For some, it is > [65]; for others [.9]. Still other disciplines assign adjectives according to the value (e.g., strong, very strong, etc.,(4 votes)

- how do we tell the difference between a positive,negative and neutral association?(5 votes)
- A positive association is when the line on the graph is moving upward, like in Problem 1. You see, the line is moving up. Therefore, it is a positive association. In Problem 2, the line is moving down. That is called a negative association. No association is like in Problem 3, when there isn't a clear line at all. I hope this helps!(3 votes)

- why is the check button so tiny(5 votes)
- idk

maybe...its because you need to zoom out(2 votes)

- This is confusing can someone help me? please!(3 votes)
- What is it that is confusing? I'd be happy to help.(2 votes)

- why is math so hard and important(3 votes)