Scat, Cor, Reg

Question 1

Scatterplots: Show

Answer 1

• Show relationship btw quantitative variables measured on the same case
• Dependant variable- on the Y, is the outcome of interest
• Explanatory variable- on the X, changes in dependant variable

Question 2

Scatterplots: Interpretation

Answer 2

• Direction: Positive or Negative (association)
• Form: Linear or non
• Strength of the relationship: Strong or Weak

Question 3

Outlier

Answer 3

value that falls outside overall pattern of the relationship

Question 4

Influential observation

Answer 4

Observation that changes the result of a calculation of removed from the sample

Question 5

Correlation

Answer 5

• Measures strength and direction of the linear relationship btw 2 quant variables
• No distinction btw X and Y
• Ranges btw -1, 1
• Affected by outliers
  (formula)

Question 6

Regression

Answer 6

• Describes how variable Y changes in response to variable X: Least Square Regression = most common
• R^2 measures how close two points are on the regression line: 0,1
  (formula)

Question 7

Extrapolation

Answer 7

Using the regression line to predict outside the graph