Bivariate Data

Question 1

What are properties of bivariate data?

Answer 1

Both variables are considered
Both could be random
Usually displayed on scatter graph
Relationship could be linear (LoBF)

Question 2

What is the PMCC?

Answer 2

Product Moment Correlation Coefficient is used to test to see how strong a correlation is

Question 3

What is the formula for covariance?

Answer 3

S(x_i - xbar)(y_i - ybar) /// n

Question 4

What is covariance?

Answer 4

Covariance gives to what extent points are positively or negatively correlated

Question 5

What is the formula for PMCC?

Answer 5

Covariance /// Standard Deviation

Sum_xy /// Sqr(Sum_xx x Sum_yy)

Question 6

What do the values of PMCC mean?

Answer 6

PMCC = -1 (Perfect Negative Correlation)
PMCC = 0 (No Deviation)
PMCC = 1 (Perfect Positive Correlation)

Question 7

What values of PMCC are considered strong correlation?

Answer 7

r < -0.7
r > 0.7

Question 8

What is the formula for S_xy ?

Answer 8

Sum(x_i y_i) - n(xbar)(ybar)

Question 9

What is the formula for S_xx ?

Answer 9

Sum(x_i²) - n(xbar)²

Question 10

How is population correlation coefficient estimated?

Answer 10

Often, a small sample is used to calculate correlation coefficient ‘r’

Question 11

What are the steps to estimating ‘p’ using ‘r’?

Answer 11

Write down the null and alternate hypothesis
Write down significance level
Calculate PMCC(r)
Find critical values from table
Compare ‘r’ to critical value and finding conclusion