Question

For workers on an assembly line the number of weeks on the line, the explanatory variable, and the number of rejects (unacceptable assemblies), the response variable, were recorded during a typical month of work. It was found that the correlation coefficient between the variables was r = -0.61. On the average, does the number of rejects increase, decrease or stay the same as the number of weeks on the line increases?

Answer choices A Stays the same B Increases C Decreases

Answer #1

Given :

correlation coefficient between the variables , r = - 0.61

since the correlation coefficient is negative , the two variables move in opposite direction .

A negative correlation means that there is an inverse relationship between two variables.

That is , as one variable increases other variable decreases.

Similarly if one variable decreases other varible increases.

Therefore , On the average , the number of rejects
**Decreases** as the the number of weeks on the line
increases.

So the correct answer choice is **C Decreases**

Data collected in a statistics class concerning the number of
hours spent studying for the course (explanatory variable) and the
final grade of each student (response variable) showed a
correlation coefficient of r = + 0.74. 30 students participated in
this study. On the average, does the final grade increase, decrease
or stay the same as the number of hours studying increase?

Part 1
For a set of
two-variable data, the correlation r can be used to
assess:
Group of answer choices
both the direction and the stength.
the strength only.
the direction only.
the form/shape only.
Part 2
The correlation
r has:
Group of answer choices
the same units as the
response variable y.
no units.
the same units as
x times y.
the same units as the
explanatory variable x.
Part 3
The correlation
between two variables will be closer...

a. A line has an intercept of 9 and a slope of 5.4. When x is
10, what is y?_________
b.
A line is given as y = 44 + 9.2 x
If x increases by 2 units, y increases by ___
(if y decreases, the answer should be a negative number)
(provide one decimal place)_______
c.
A regression analysis states that R-squared = 0.86. Which of
these is correct?
86% of the variability in the response variable is due...

Given the following data set, let x be the explanatory
variable and y be the response variable.
x
8
2
2
6
6
3
1
y
3
8
9
6
4
7
9
(a) If a least squares
line was fitted to this data, what percentage of the variation in
the y would be explained by the regression line? (Enter
your answer as a percent.)
ANSWER: %
(b) Compute the
correlation coefficient: r=

Given the following data set, let x be the explanatory variable
and y be the response variable. x 1 6 7 3 1 5 2 y 10 4 4 7 9 5 8
(a) If a least squares line was fitted to this data, what
percentage of the variation in the y would be explained by the
regression line? (Enter your answer as a percent.) ANSWER: % (b)
Compute the correlation coefficient: r=

a. If r is a negative number, then b (in the line of regression
) is negative.
true or false
b.The line of regression is use to predict the theoric average
value of y that we expect to occur when we know the value of x.
true or false
c. We can predict no matter the strength of the correlation
coefficient.
true or false
d. The set of all possible values of r is, {r: -1< r <
1
treu...

Which one of the following is a true statement about the
correlation coefficient r?
The unit of measure for r is the same as the unit of measure for
the response variable y. Values of r range from -∞ to +∞.
If the sign of r is negative, then increases in one variable
tend to be associated with decreases in the other variable.
The designations of which is the explanatory variable and which
is the response variable cannot be interchanged...

In a survey, a statistician analyzed the relationship between
the Mothers-Heights (explanatory variable x) and the
Daughters-Heights (response y) by using the regression method. When
he drew the regression line, he found that at x1 = 0 the predicted
response is ˆy1 = 29.9, and at x2 = 1 the predicted response is ˆy2
= 30.43. Answer the following questions providing all the
details.
1. Find the intercept a and slope b of the regression line of
Daughters-Heights on Mothers-Heights....

Use technology to find the equation of the regression line in
which the explanatory variable (or x variable) is the cost of a
slice of pizza and the response variable (or y variable) is the
corresponding cost of a subway fare.
Year 1960 1973 1986 1995 2002 2003
cost of pizza. 0.15 0.35 1 1.25 1.75 2
subway fare. 0.15 0.35 1 1.35 1.50 2
A) Simple linear regression analysis relating to x = Cost of a
slice of pizza...

estimate std.error
Intercept 26184.4 3517.3
snowfall 3824.8 247.5
r^2=.8565
adjusted r^2= .8529
s=8991
For each additional inch of snowfall, steam runoff
decreases by 26,184 acre-feet, on average.
increases by 26,184 acre-feet, on average.
.decreases by 3824 acre-feet, on average.
increases by 3824 acre-feet, on average
If multicollinearity is present, then we can conclude that the
fitted regression model:
may have estimated slopes very different from what we should
expect due to numerical instabilities, making correct
interpretation of the effect on...

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