Correlation

Question 1

What question does correlation ask?

Answer 1

Is there a relationship?

Question 2

What is correlation typically indexed by?

Answer 2

Correlation coefficient

Question 3

What is the range of values for correlation coefficient?

Answer 3

-1 and 1

Question 4

What does a -1 correlation coefficient indicate?

Answer 4

Perfective negative relationship

Question 5

What does a 0 correlation coefficient indicate?

Answer 5

No relationship

Question 6

What does a 1 correlation coefficient indicate?

Answer 6

Perfective positive relationship

Question 7

What is the null hypothesis for testing the significance of r?

Answer 7

That p = 0 (unknown population correlation coefficient, produced rho)

Question 8

What is the degrees of freedom for this test?

Answer 8

n - 2

Question 9

What is the value for the t statistic for this test?

Answer 9

(r x sqrt(n-2))/(sqrt(1-r^2))

Question 10

Why does correlation not necessarily equal causation?

Answer 10

Variables may be correlated by:

• chance
• another third variable that affects them both
• genuine causation

Question 11

What is the durbin watson test used for?

Answer 11

Used to detect the presence of autocorrelation in the residuals

Question 12

What is pseudoreplication?

Answer 12

The process of artifically inflating the number of observations and hence the degrees of freedom by assuming independence of datums when they are not really independent

Question 13

Give an example of pseuodoreplication

Answer 13

Taking multiple measurements of the same variable from the same indivudal and treating them as independent datum