Question

Q24. The coefficient of determination (r²) is calculated as 0.49, then the correlation coefficient:

1. Cannot be determined without the data
2. Should be - 0.70 or 0.70
3. Should be 0.
4. Neither of the above

Q25. A regression line is used for all of the following except one. Which one is not a valid use of a regression line?

1. To estimate the average value of Y at a specified value of X.
2. To predict the value of Y for an individual, given that individual's X-value.
3. To estimate the change in Y for a one-unit change in X.
4. To determine if a change in X causes a change in Y.

Q26. Which choice is not an appropriate description of Yˆ in a regression equation?

1. Estimated response
2. Predicted response
3. Estimated average response
4. Observed response

Q27. Which of the following is the best way to determine whether or not there is a statistically significant linear relationship between two quantitative variables?

1. Compute a regression line from a sample and see if the sample slope is 0.
2. Compute the correlation coefficient and see if it is greater than 0.5 or less than −0.5.
3. Conduct a test of the null hypothesis that the population slope is 0.
4. Conduct a test of the null hypothesis that the population intercept is 0.

Q28. There is no relationship between variables unless the data points lie in a straight line.

1. True
2. False

Answer 1

ans (24)

since the coefficient of determination (r2), is similar to the correlation coefficient R. and we have

coefficient of determination (r2)= 0.49 = correlation coefficient (r)

therefore the correct answer is (d) neither of the above.

ans(25)

A regression line is used for all of the following except to determine if a change in X causes a change in Y.

therefore the correct answer is (d) To determine if a change in X causes a change in Y.

ans(26)

the choice which is not an appropriate description of Yˆ in a regression equation is observed response.

therefore the correct answer is (d) observed response

ans(27)

the best way to determine whether or not there is a statistically significant linear relationship between two quantitative variables is to conduct a test of nul hypothesis that the population slope is 0.

therefore the correct answer is (c)

ans(28)

There is no relationship between variables unless the data points lie in a straight line

therefore correct answer is (b) FALSE