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## Praxis Core Math

### Unit 1: Lesson 3

Statistics and probability- Data representations | Lesson
- Data representations | Worked example
- Center and spread | Lesson
- Center and spread | Worked example
- Random sampling | Lesson
- Random sampling | Worked example
- Scatterplots | Lesson
- Scatterplots | Worked example
- Interpreting linear models | Lesson
- Interpreting linear models | Worked example
- Correlation and Causation | Lesson
- Correlation and causation | Worked example
- Probability | Lesson
- Probability | Worked example

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# Scatterplots | Lesson

## What's a scatterplot?

A scatterplot displays data about two variables as a set of points in the x, y-plane.

A scatterplot is a key tool to determine if there is a relationship between the values of two variables.

### What skills are tested?

- Matching the description of a relationship between variables to a scatterplot
- Describing the relationship between variables shown on a scatterplot
- Drawing conclusions from a scatterplot

## What does correlation mean?

**Correlation**describes how one variable changes as the other changes in a scatterplot.

x increases, y tends to increase.

: As x increases, y tends to decrease.

: As x increases, y stays about the same or has no clear pattern.

: As ## What is a linear relationship?

Linearity describes whether or not the trend of the dots in a scatterplot can be approximated by a line.

In a

, data points tend to fall along a line. The scatterplot below shows a linear relationship with a illustrating how the data might be approximated.In a

, data points do not fall along a line. The scatterplot below shows a nonlinear relationship with a *curve*illustrating how the data might be approximated.## What conclusions can we make based on a scatterplot ?

In context, the meaning of the points in a scatterplot corresponds to the variables represented by each axis.

For example, a teacher collected data on the shoe size and quiz score for every student in her class. In her scatterplot below, the horizontal axis is

*Shoe Size*and the vertical axis is*Quiz Score.*Each of the 23 dots represents the shoe size and quiz score of one particular student.## Your turn!

## Things to remember

A scatterplot:

- displays data about two variables as a set of points in the x, y-plane
- is a key tool to determine if there is a relationship between two variables.

The relationship between variables is described in terms of

and :- Do the variables exhibit a
**positive**,**negative**, or**no**correlation? - Is the relationship
**linear**or**nonlinear**?

Only correlation between variables—not the cause of the relationship—can be determined from a scatterplot.

- Making conclusions about causation requires a well-designed experiment.

## Want to join the conversation?

- What is the differencebetween correlation and linearity(2 votes)