**Unit 4**

Topics:

**Introduction to Bivariate Data **link:Intro Bivariate

- Learning Objectives

- Define “bivariate data”
- Define “scatter plot”
- Distinguish between a linear and a nonlinear relationship
- Identify positive and negative associations from a scatter plot

**Values of the Pearson Correlation **link:Values of the Pearson

- Learning Objectives

- Describe what Pearson’s correlation measures
- Give the symbols for Pearson’s correlation in the sample and in the population
- State the possible range for Pearson’s correlation
- Identify a perfect linear relationship

**Properties of Pearson’s r **link:Properties of r

- Learning Objectives

- State the range of values for Pearson’s correlation
- State the values that represent perfect linear relationships
- State the relationship between the correlation of Y with X and the correlation of X with Y
- State the effect of linear transformations on Pearson’s correlation

**Computing Pearson’s r **link:Computing Pearson’s r

- Learning Objectives

- Define X and x
- State why Σxy = 0 when there is no relationship
- Calculate r

**Variance Sum Law II **link:Variance Sum Law II

- Learning Objectives

- State the variance sum law when X and Y are not assumed to be independent
- Compute the variance of the sum of two variables if the variance of each and their correlation is known
- Compute the variance of the difference between two variables if the variance of each and their correlation is known

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