In: Statistics and Probability
2.
(07.05)
Which of the following conditions is/are necessary to justify the use of t procedures in a significance test for the slope of a regression line? (4 points)
I. For each given value of x, the values of the response
variable y are Normally distributed.
II. For each given value of x, the values of the response variable
y are independent.
III. For each given value of x, the standard deviation of y is the
same.
I only |
|
II only |
|
III only |
|
I and II only |
|
I, II, and III |
3.
(07.05)
A researcher wants to determine whether there is a linear relationship between number of rom-com movies and engagements. The table displays a partial computer printout of the regression analysis and is based on a sample of eight subjects.
Predictor | Coeff | St. Dev | t Ratio | p-Value |
Constant | 4.35744984 | 2.385747738 | 5.7382918 | 0.00375268 |
Rom-com movies | 1.34457321 | 0.526645738 |
What is the value of the t-test statistic for H0: β = 0? (4 points)
0.004 |
|
5.74 |
|
−5.74 |
|
−2.55 |
|
2.55 |
4.
(07.05)
Researchers are conducting a study in an attempt to establish a linear relationship between the number of online keyboard lesson videos and the number of keyboard sales. A computer output for regression is shown and is based on a sample of eight observations.
Predictor | Coeff | St. Dev | t Ratio | p-Value |
Constant | -4.19411878 | 7.812571764 | -0.53684227 | 0.601188456 |
Keyboard Video Views | 0.301433595 | 0.032631691 | 9.237449496 | 8.37927E-07 |
What represents the 98% confidence interval for the slope of the regression line? (4 points)
0.3014 ± 9.237(0.0326) |
|
0.3014 ± 9.237(7.8126) |
|
0.3014 ± 3.143(0.0326) |
|
0.3014 ± 3.143(7.8126) |
|
0.3014 ± 0.537(0.6012) |
5.
(07.05)
Researchers pose the question: Can shirt size be predicted from a man's height? A random sample of 15 males and their shirt size versus height (in inches) gives the regression results shown in the table.
Predictor | Coeff | SE Coeff | t Ratio | p-Value |
Constant | -48.81 | 30.57 | -1.60 | 0.128 |
Height | 0.3736 | 0.1898 | 1.97 | 0.065 |
S = 4.46720 | R-Sq. = 17.7% |
R-Sq. (adj) = 13.1% |
Is there statistical evidence of a linear relationship between
shirt size and height? (4 points)
No, because r2, the coefficient of determination, is too small |
|
No, because 0.128 is above any reasonable significance level |
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Yes, because, by any reasonable observation, taller men tend to have a larger shirt size |
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Yes, because the slope is positive |
|
Yes, there is evidence at the 10% significance level, but not at the 5% level |