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Flashcards in Correlation Deck (13)
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1
Q

What question does correlation ask?

A

Is there a relationship?

2
Q

What is correlation typically indexed by?

A

Correlation coefficient

3
Q

What is the range of values for correlation coefficient?

A

-1 and 1

4
Q

What does a -1 correlation coefficient indicate?

A

Perfective negative relationship

5
Q

What does a 0 correlation coefficient indicate?

A

No relationship

6
Q

What does a 1 correlation coefficient indicate?

A

Perfective positive relationship

7
Q

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

A

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

8
Q

What is the degrees of freedom for this test?

A

n - 2

9
Q

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

A

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

10
Q

Why does correlation not necessarily equal causation?

A

Variables may be correlated by:

  • chance
  • another third variable that affects them both
  • genuine causation
11
Q

What is the durbin watson test used for?

A

Used to detect the presence of autocorrelation in the residuals

12
Q

What is pseudoreplication?

A

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

13
Q

Give an example of pseuodoreplication

A

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