Testing Lack of Correlation

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Testing lack of correlation

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Question 1

Question 1.

True or false: A test on slope is not the same as a test on correlation.

False

True

Correct. The tests are the same.

Incorrect. The tests are the same.

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Question 2

185

Question 2.

True or false: When testing correlation, the null hypothesis is a statement of no correlation between X and Y.

False

True

Correct. This is a correct statement.

Incorrect. This is a correct statement.

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Question 3

247

Question 3.

The sample correlation is r = –0.226. On the basis of just this sample correlation value, can we reject the null hypothesis of zero correlation?

Yes

Correct. Without a measure of variability, we cannot get a P-value. And without a P-value we cannot decide whether to reject H₀.

Incorrect. Without a measure of variability, we cannot get a P-value. And without a P-value we cannot decide whether to reject H₀.

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Question 4

265

Question 4.

Why don’t we need to examine the least-squares regression line for testing correlation?

Because we don’t need the means,

\bar{x}

$\overline{x}$ and

\bar{y}

$\overline{y}$ , and the standard deviations,

s_{x}

$s_{x}$ and

s_{y}

$s_{y}$ .

Because we don’t need a linear relationship for correlation.

Because we don’t need to do prediction.

Correct. We do need the means and standard deviations and we do need a linear relationship for correlation, but we don’t need to do prediction.

Incorrect. We do need the means and standard deviations and we do need a linear relationship for correlation, but we don’t need to do prediction.

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Question 5

297

Question 5.

True or false: Unlike testing slope which requires conditions to be met, testing correlation has no conditions that need to be met.

False

True

Correct. All inferential procedures have conditions that need to be met, including testing correlation.

Incorrect. All inferential procedures have conditions that need to be met, including testing correlation.

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Question 6

313

Question 6.

The P-value for this test on correlation is P-value < 0.0001. At α = 0.05, can we reject H₀?

Yes

Correct. Since P-value < 0.0001 is less than α = 0.05, we can reject H₀.

Incorrect. Since P-value < 0.0001 is less than α = 0.05, we can reject H₀.

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Question 7

337

Question 7.

Since the relationship is significant, can we conclude that the draft was fair?

Yes

Correct. Since the relationship is significant, the draft was not fair because those with birthdays late in the year were more likely to have a high draft number (i.e., a draft number close to 1.0.)

Incorrect. Since the relationship is significant, the draft was not fair because those with birthdays late in the year were more likely to have a high draft number (i.e., a draft number close to 1.0.)

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StatTutor Lesson - Testing Lack of Correlation

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