Question 1

Is the correlation in the figure about 
(a) .2, (b) -.4, (c) .4, (d) .8, or (e) -.9?

Accepted Answer

The answer of Is the correlation in the figure about...

Question 2

Estimate the correlation coefficient of the figure below.

Accepted Answer

The answer of Estimate the correlation coefficient of the figure...

Question 3

Find the scatter diagram that corresponds to the correlation coefficient r = -.8.

Accepted Answer

The answer of Find the scatter diagram that corresponds to...

Question 4

Calculations from a data set of n = 36 pairs of (x, y) values have provided the following results.
  
Obtain the correlation coefficient.

Accepted Answer

The answer of Calculations from a data set of n...

Question 5

Calculations from a data set of n = 32 pairs of (x, y) values have provided the following results.
  
Obtain the correlation coefficient.

Accepted Answer

The answer of Calculations from a data set of n...

Question 6

The false correlation produced by a lurking variable is called ________ correlation.

Accepted Answer

The answer of The false correlation produced by a lurking...

Question 7

An observed correlation between two variables may be caused by the influence of a third variable.

Accepted Answer

This is known as a confounding variable, which can affect both variables being studied, leading to a spurious correlation.

Question 8

Suppose from a data set of distance measurements in yards and time measurements in hours, the value of r is found to be 0.82. What would the value of r be if the distances were measured in feet and time in minutes.

Accepted Answer

The correlation coefficient (r) is a unitless measure of the strength and direction of a linear relationship between two variables. Changing the units of measurement does not affect the value of r.

Question 9

A scientist in a center for disease control observes that the number of bacteria in a culture and air pollution in the city rise with time. Is there exists a lurking variable in this case?

Accepted Answer

The answer of A scientist in a center for disease...

Question 10

Usually, the predictor or ______ variable is denoted by the letter ______.

Accepted Answer

The answer of Usually, the predictor or ______ variable is...

Question 11

An experimental study of the relation between two variables is often motivated by a need to predict one from the other. The first step in such a study is to plot and examine the scatter diagram.

Accepted Answer

A scatter diagram is used to visually assess the relationship between two variables, which is crucial for predicting one variable based on the other.

Question 12

The numerical value of r indicates how effectively y can be predicted from x.

Accepted Answer

The numerical value of r, known as the correlation coefficient, measures the strength and direction of a linear relationship between two variables, indicating how effectively one variable can predict the other.

Question 13

A line is determined by two constants. One of these constants is the ______, that is, its height above the origin.

Accepted Answer

The answer of A line is determined by two constants....

Question 14

A line is determined by two constants. One of these constants is the ______, that is, the amount that y increases whenever x is increased by one unit.

Accepted Answer

The answer of A line is determined by two constants....

Question 15

Consider the line

A) What is its intercept?
B) What is its slope?

Accepted Answer

The answer of Consider the line

A) What...

Question 16

What is the graph of the line  
.

Accepted Answer

The answer of What is the graph of the line...

Question 17

A fabric manufacturer has determined that the resistance y of a fiber is given by
y = 18x - 155
where x (in grams) denotes the amount of a synthetic compound used to make the fiber.
A) If 44 grams of the synthetic compound are used, what is the resistance?
B) At least how many grams of synthetic compound must be used to have a positive resistance?

Accepted Answer

The answer of A fabric manufacturer has determined that the...

Question 18

For the data set, compute the least squares estimates.
  
A)   
B)

Accepted Answer

The answer of For the data set, compute the least...

Question 19

In an experiment to study the relation between the speed of an athlete running 100 meters, y (meters/second) and the environment temperature, x (Celsius degrees), her trainer collected the following statistics:
  Find the equation of the least squares fitted line.

Accepted Answer

The answer of In an experiment to study the relation...

Question 20

For one coastal state, there is a high correlation between ice cream sales and number of people swimming in the ocean. Suggest a possible lurking variable and explain what is meant by the term lurking variable.

Accepted Answer

The answer of  For one coastal state, there is...

Quiz 3: Descriptive Study of Bivariate Data

Is the correlation in the figure about (a) .2, (b) -.4, (c) .4, (d) .8, or (e) -.9?

Estimate the correlation coefficient of the figure below.

Find the scatter diagram that corresponds to the correlation coefficient r = -.8.

Calculations from a data set of n = 36 pairs of (x, y) values have provided the following results. Obtain the correlation coefficient.

Calculations from a data set of n = 32 pairs of (x, y) values have provided the following results. Obtain the correlation coefficient.

The false correlation produced by a lurking variable is called ________ correlation.

An observed correlation between two variables may be caused by the influence of a third variable.

Suppose from a data set of distance measurements in yards and time measurements in hours, the value of r is found to be 0.82. What would the value of r be if the distances were measured in feet and time in minutes.

A scientist in a center for disease control observes that the number of bacteria in a culture and air pollution in the city rise with time. Is there exists a lurking variable in this case?

Usually, the predictor or variable is denoted by the letter .

An experimental study of the relation between two variables is often motivated by a need to predict one from the other. The first step in such a study is to plot and examine the scatter diagram.

The numerical value of r indicates how effectively y can be predicted from x.

A line is determined by two constants. One of these constants is the ______, that is, its height above the origin.

A line is determined by two constants. One of these constants is the ______, that is, the amount that y increases whenever x is increased by one unit.

Consider the line A) What is its intercept? B) What is its slope?

What is the graph of the line .

For the data set, compute the least squares estimates. A) B)

In an experiment to study the relation between the speed of an athlete running 100 meters, y (meters/second) and the environment temperature, x (Celsius degrees), her trainer collected the following statistics: Find the equation of the least squares fitted line.

For one coastal state, there is a high correlation between ice cream sales and number of people swimming in the ocean. Suggest a possible lurking variable and explain what is meant by the term lurking variable.