Relationships between variables

Question 1

Science tries to explain phenomena by examining _______ between variables.

Answer 1

relationships

Question 2

_______ plots are great for picturing relationships.

Answer 2

Scatter

Question 3

Covariance

Answer 3

A measure of the joint variability of two random variables
- when signs of xi and yi match, their product is positive and adds a positive term to the sum
- positive terms = positive covariance
- difficult units
- change in units changes covariance

Question 4

Correlation

Answer 4

Expresses the magnitude and direction of the linear relationship between two variables
- Pearson correlation coefficent
- Standardized, easy to incorperate
- Divide by standard deviation to get rid of units
- (Almost) the mean of the products of the z scores on the two variables
- cor(x, y) or cor(data) in R

Question 5

Interpreting the parameter estimates

Answer 5

It’s risky to make predictions beyond the data’s range