Chapter 13: Regression and Correlation

Question 1

What is correlation and regression?

Answer 1

Statistical techniques are often used in relation with one another

Question 2

What can you do with correlation and regression?

Answer 2

quantify the strength and direction of an association between variables

Question 3

What is covary?

Answer 3

Two random variables are associated

Question 4

What is regression?

Answer 4

For any given value of x we can predict the corresponding value of y, specific predictions based on an association

Question 5

What is the correlation coefficient?

Answer 5

Number that quantifies the strength and direction of an association between variables

Question 6

What numbers are correlations between?

Answer 6

1 and -1

Question 7

What are the measures of association?

Answer 7

The variety of correlation coefficients

Question 8

What do correlations measure?

Answer 8

Relationship between 2 variables (x and y)

Question 9

Suppose that you have access to hospital records on patient age and their number of days spent in hospital. Your most appropriate measure of association would likely be ________.

Answer 9

Pearsons r

Question 10

What can you say if no pattern appears to exist between variables?

Answer 10

Statistically independent

Question 11

What is the strength variation in correlation?

Answer 11

0 and +- 1

Question 12

What does a stronger pattern or association mean?

Answer 12

Larger the correlation coefficient

Question 13

There is no such thing as a zero correlation.

Answer 13

False

Question 14

A correlation coefficient distinguishes between independent and dependent variables.

Answer 14

false

Question 15

Are a coefficient of -.35 and +.35 equally strong?

Answer 15

Yes can think of it as a continuum

Question 16

What is the relationship between positive and negative correlations?

Answer 16

Positive go together, in negative they move apart

Question 17

What do scatterplots plot?

Answer 17

Interval or ratio level data onto a graph in a case-by-case manner

Question 18

What does the horizontal axis represent?

Answer 18

Predictor variable

Question 19

What does the vertical axis stand for?

Answer 19

Criterion variable

Question 20

What is the line of best fit?

Answer 20

straight line that best represents data on scatter plot (regression line), nature of relation between two variables, eyeball method, decides if it is linear

Question 21

What happens if a straight line can’t be drawn through the data points?

Answer 21

There may be no relationship at all

Question 22

What are scatterplots very useful for spotting?

Answer 22

Outliers in data

Question 23

What do outliers have a significant impact on?

Answer 23

Correlation coefficients

Question 24

What do scatterplots tell us in regard to calculations?

Answer 24

Whether or not calculating pearsons r is appropriate

Question 25

What are the requirements for pearsons r?

Answer 25

Random sampling, continuous interval or ratio data, normally distributed variables, no significant outliers, linear

Question 26

What can pearsons r not detect?

Answer 26

Non-linear associations

Question 27

Study The Who grows up to be a philanderer thing cause it is mentioned a LOT

Question 28

What is a advantage of Pearson coefficients?

Answer 28

Possess a common metric, compare strength of relationships with one another

Question 29

What is the remaining percentage 100-r^2?

Answer 29

Unexplained variation

Question 30

What is unexplained variation?

Answer 30

Variation in y is accounted for by some variable that isn't x

Question 31

What do you use when you cant use Pearsons r?

Answer 31

Rank correlation

Question 32

What is monotonicity?

Answer 32

Whether or not one set of scores tends to increase or decrease along with another set (linear)

Question 33

What are non-monotonic associations?

Answer 33

Scores can't increase together then decrease

Question 34

What is a spurious correlation?

Answer 34

Association is caused by a third variable that affects both the associations two variables simultaneously;

Question 35

What is reverse causation?

Answer 35

Might think x causes y but actually y causes x

Question 36

What is the post-hoc fallacy?

Answer 36

If B followed A then A must have caused B

Question 37

What happens with stronger associations?

Answer 37

The more likely it is causal

Question 38

What is empirical support?

Answer 38

Gathered evidence using our senses

Question 39

What is the slope?

Answer 39

Steepness of the line of best fit, amount of change in y for every change in x (descriptive statistic)

Question 40

What is the intercept?

Answer 40

Point regression line crosses y axis when x=0

Question 41

What are the steps of the regression equation?

Answer 41

Calculate slope (b), calculate intercept (a), using value of x solve for y