STATS CH 6

A scatterplot that describes a positive correlation is characterized by a) a tilt from the lower left to the upper right. b) a tilt from the upper left to the lower right. c) little or no tilt. d) any of the above, depending on circumstances.

A

For a strong (but imperfect) negative relationship, a z score of 2.34 will be paired with a z score a) in the vicinity of -2.34. b) in the vicinity of 2.34. c) of 2.34. d) of 2.34.

A

If it were impossible to predict taxes from annual income, the value of r for income and taxes would be nearest to a) 0.00 b) -1.00 c) 1.00 d) none of the above.

A

It is reasonable to conclude that a) annual salaries tend to increase with educational level, and salaries tend to be higher for males than females. b) annual salaries tend to increase with educational level, and salaries tend to be higher for females than males. c) annual salaries tend to decrease with educational level, and male salaries lower than female salaries. d) annual salaries tend to decrease with educational level, and female salaries trend lower than male salaries.

A

The intuitive approach to searching for a relationship becomes cumbersome and inexact when a) there are more than a few pairs of observations. b) little or no relationship is present. c) the relationship is negative. d) observations assume values with decimal points.

A

When outliers occur, the best strategy is to report a) the values of r both with and without any outliers. b) the value of r with any outliers. c) the value of r without any outliers. d) nothing whatsoever.

A

You're told that, for a large group of students, an r of .23 describes the relationship between anxiety score and time to complete a problem solving task. This implies that there probably is a) a slight tendency for more anxious students to be slower problem solvers. b) a slight tendency for more anxious students to be faster problem solvers. c) little or no relationship between anxiety and speed of problem solving. d) a very strong relationship between anxiety and speed of problem solving.

A

After duplicate correlations have been discarded and trivial correlations have been ignored, there remain a) two correlations. b) three correlations. c) six correlations. d) nine correlations.

B

Assume that r equals -.43 for the relationship between years of heavy smoking and life expectancy. This signifies that a) heavy smokers tend to have longer life expectancies. b) heavy smokers tend to have shorter life expectancies. c) there is a cause effect relationship between heavy smoking and life expectancy. d) there is a negative cause effect relationship between heavy smoking and life expectancy.

B

Given that the relationship between GPA and IQ is stronger in high school than in college, the dot cluster for high school (compared to that for college) should a) less closely approximate a straight line. b) more closely approximate a straight line. c) define a straight line. d) lack any apparent tilt

B

Only ____ of these correlations should be taken seriously. a) one b) two c) three d) an unknown number

B

The computation formula for r is preferred to the z score formula because the computation formula is more a) understandable. b) efficient. c) general. d) valid.

B

When the range of possible X and Y scores is restricted, the value of the correlation coefficient usually a) increases. b) decreases. c) remains about the same. d) changes unpredictably

B

Without doing any calculations, describe the relationship for the following pairs of observations. X Y 6 118 12 109 3 144 10 111 1 142 a) positive b) negative c) little or no relationship d) impossible to describe

B

A dot cluster that tilts from upper left to lower right reflects a) little or no relationship. b) a positive relationship. c) a negative relationship. d) a curvilinear relationship.

C

A positive r reflects the tendency for pairs of observations to occupy a) similar locations in their respective distributions. b) dissimilar and opposite locations in their respective distributions. c) similar relative locations in their respective distributions. d) dissimilar and opposite relative locations in their respective distributions.

C

A single word that best describes the general notion of a relationship is a) similarity. b) dissimilarity. c) regularity. d) symmetry.

C

Although there are exceptions, a value of r in excess of .50, in either a positive or negative direction, would represent a) an unimportant relationship in most areas of behavioral research. b) a weak relationship in most areas of behavioral research. c) a very strong relationship in most areas of behavioral research. d) a virtually perfect relationship in most areas of behavioral research.

C

If everyone paid taxes equal to 10 percent of their total annual income, the value of r for income and taxes would be nearest to a) 0.00 b) -1.00 c) 1.00 d) none of the above

C

If there is a correlation between the age of schoolchildren and their reading comprehension, you could speculate about the basis for this relationship. Probably the most reasonable speculation is that a) age causes reading comprehension. b) age could cause reading comprehension, or both could be effects of some more basic cause. c) some more basic combination of factors, such as intellectual maturation and educational background, causes the relationship. d) none of the above

C

Which one of the following relationships is perfect? a) heights and weights of newborn infants b) heights and weights of well trained athletes c) heights of adults, each described twice--once in inches and once in centimeters d) heights of twins

C

. Scatterplots a) depict relationships as dot clusters. b) provide a preview of the fully measured relationship. c) show any pronounced curvilinearity. d) all of the above

D

Although designed originally for use with quantitative data, the Pearson r has been extended to other kinds of situations, including those that involve a) ranks. b) ordered qualitative data. c) ordered qualitative and quantitative data. d) all of the above

D

As the pattern among pairs of z scores becomes more apparent, the value of r tends toward a) 0.00 b) 1.00. c) 1.00. d) either 1.00 or 1.00.

D

Dots in scatterplots that deviate conspicuously from the main dot cluster are viewed as a) errors. b) more informative than other dots. c) the same as any other dots. d) potential outliers.

D

For little or no relationship, a z score of 2.34 will be paired with a z score in the vicinity of a) 0.00. b) 2.34. c) 2.34. d) some unpredictable value.

D

The z score formula for r a) enhances our understanding. b) pinpoints the independence of r from the original units of measurement. c) is not recommended for calculating r. d) has all of the above properties.

D

Which one of the following most likely describes a positive relationship? a) automobile weight and gas mileage b) test score and time to complete test c) current age and remaining years of life expectancy d) years of education and lifetime earnings

D

Which one of the following numbers couldn't possibly be a value of r? a) 0.00 b) 1.00 c) 1.00 d) 1.03

D