Question 1

Correlation is a measure of the extent to which two variables
A) are related.
B) are random samples.
C) influence each other.
D) are dependent variables.

Accepted Answer

Correlation measures the degree of relationship between two variables, indicating how closely they move together. It does not necessarily imply causation or influence between the variables. Therefore, choice A is the correct answer.

Question 2

When we ask,for example,how closely related are the personality scores of identical twins,we are asking how strongly two ________ are related.
A) experimental groups
B) control groups
C) variables
D) scatterplots

Accepted Answer

The question is addressing the relationship between personality scores of identical twins, which are both variables being measured. Therefore, the correct answer is C) variables. A) experimental and B) control groups refer to groups in an experimental design, while D) scatterplots refer to a graph used to display the relationship between two variables.

Question 3

To determine whether the strength of people's self-esteem is related to their income levels,researchers would most likely make use of
A) case studies.
B) correlational research.
C) experimentation.
D) naturalistic observation.

Accepted Answer

Correlational research would be the best method to determine whether there is a relationship between self-esteem and income levels because it allows researchers to examine the strength and direction of the relationship between the two variables. Other methods may not provide the necessary data to draw conclusions about such a relationship.

Question 4

If a set of standardized test scores is normally distributed,having a mean of 50 and a standard deviation of 10,approximately 68 percent of the group members receive scores somewhere between
A) 50 and 60.
B) 45 and 55.
C) 40 and 60.
D) 35 and 65.

Accepted Answer

The 68-95-99.7 rule for a normal distribution states that approximately 68% of the data falls within one standard deviation of the mean. Since the mean is 50 and the standard deviation is 10, one standard deviation above and below the mean would be 40 and 60, respectively.

Question 5

If IQ scores are normally distributed,having a mean of 100 and a standard deviation of 15,approximately what percentage of people have IQ scores somewhere between 70 and 130?
A) 34
B) 50
C) 68
D) 95

Accepted Answer

In a normal distribution, approximately 95% of the data falls within two standard deviations of the mean. Since 70 and 130 are two standard deviations away from the mean of 100 (100-2*15=70 and 100+2*15=130), about 95% of people have IQ scores in this range.

Question 6

An inverse relationship in which scores for one variable increase as scores for another variable decrease represents
A) a confounding variable.
B) a positive correlation.
C) a normal curve.
D) a negative correlation.

Accepted Answer

An inverse relationship, also known as a negative correlation, is when scores for one variable increase as scores for another variable decrease. It is the opposite of a positive correlation, in which scores for both variables increase together. Confounding variables and the normal curve are not relevant to this specific scenario.

Question 7

Correlational research is most useful for purposes of
A) explanation.
B) prediction.
C) control.
D) replication.

Accepted Answer

Correlational research is most useful for predicting relationships between variables, not necessarily explaining why those relationships exist or controlling for them. Replication is also not necessarily the primary purpose of correlational research, though it may be an important next step in confirming a predicted relationship.

Question 8

Although Dominick's psychology class is sometimes longer or shorter than usual,on average each class is 50 minutes.If the lengths of these classes form a normal curve,which statistic would enable Dominick to estimate the probability that any single class will last somewhere between 47 and 53 minutes?
A) mode
B) median
C) range
D) standard deviation

Accepted Answer

The standard deviation would give Dominick an idea of how spread out the class lengths are from the mean of 50 minutes. With this information, he can estimate the probability of a class being between 47 and 53 minutes using the empirical rule, which states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, 95% falls within two standard deviations, and 99.7% falls within three standard deviations.

Question 9

A graphed cluster of dots,each of which represents the values of two factors,is called a
A) normal curve.
B) scatterplot.
C) standard deviation.
D) correlation coefficient.

Accepted Answer

A scatterplot is a graphical representation of the relationship between two variables, where each dot represents a pair of values for the two variables being plotted. A normal curve is a statistical distribution, not a graph type. Standard deviation is a measure of the spread of data, not a graph type. Correlation coefficient is a measure of the strength and direction of the relationship between two variables, not a graph type.

Question 10

Approximately what percentage of the cases represented by the normal curve fall between ‒3 and +3 standard deviations from the mean?
A) 34
B) 68
C) 95
D) 100

Accepted Answer

The answer of Approximately what percentage of the cases represented...

Question 11

A direct relationship in which two sets of scores increase together or decrease together represents
A) a dependent variable.
B) replication.
C) a positive correlation.
D) a confounding variable.

Accepted Answer

A positive correlation is a direct relationship in which two sets of scores increase together or decrease together. Option A is incorrect because a dependent variable refers to the variable being measured in an experiment that may be influenced by the independent variable. Option B is incorrect because replication refers to repeating a study to see if the same results are obtained. Option D is incorrect because a confounding variable is an extraneous variable that may interfere with the relationship between the independent and dependent variables.

Question 12

The symmetrical bell‑shaped figure used to represent the distribution of many physical and psychological characteristics is called a
A) bar graph.
B) normal curve.
C) range.
D) standard deviation.

Accepted Answer

The normal curve, also known as the bell curve or Gaussian distribution, is a symmetrical bell-shaped figure used to represent the distribution of many physical and psychological characteristics. It is characterized by its mean and standard deviation, and is widely used in statistics and research.

Question 13

To discover the extent to which economic status can be used to predict political preferences,researchers are most likely to use
A) standard deviations.
B) measures of central tendency.
C) correlational measures.
D) the means.

Accepted Answer

Correlational measures, such as Pearson's r or Spearman's rho, are commonly used to explore the relationship between two variables, such as economic status and political preferences. These measures quantify the strength and direction of the relationship between the two variables, revealing whether they are positively or negatively associated and the degree to which they vary together.

Question 14

The standard deviation is the square root of the average squared deviation of scores from the
A) normal curve.
B) median.
C) mean.
D) range.

Accepted Answer

The standard deviation is a measure of variability that is based on the mean, so it is calculated by taking the average squared deviation of scores from the mean. Therefore, the correct choice is C) mean.

Question 15

Evelyn wants to know how consistent her bowling scores have been during the past season.Which of the following measures would tell her what she wants to know?
A) mean
B) median
C) standard deviation
D) range

Accepted Answer

The standard deviation would tell Evelyn how consistent her bowling scores have been during the past season. This measure shows how much the scores deviate from the average. The smaller the standard deviation, the more consistent the scores. The mean (A) and median (B) would only give her information about the average score, while the range (D) would only show the difference between the highest and lowest scores, but not the consistency between them.

Question 16

Approximately what percentage of the cases represented by the normal curve fall between -1 and +1 standard deviations from the mean?
A) 16
B) 34
C) 68
D) 95

Accepted Answer

The 68-95-99.7 rule states that approximately 68% of the cases fall between -1 and +1 standard deviations from the mean. Therefore, option C is the correct answer.

Question 17

Displaying data in a scatterplot can help us see the extent to which two variables are
A) random samples.
B) located on the normal curve.
C) correlated.
D) related to the mean.

Accepted Answer

Displaying data in a scatterplot allows us to visually assess the degree of correlation between two variables. This can help us determine if they are positively correlated (as one increases, so does the other), negatively correlated (as one increases, the other decreases), or unrelated (no clear pattern observed).

Question 18

Approximately 95 percent of the cases represented by the normal curve fall within ________ standard deviation(s)from the mean.
A) 1
B) 2
C) 3
D) 5

Accepted Answer

According to the empirical rule, approximately 95 percent of the cases fall within 2 standard deviations from the mean.

Question 19

Which of the following is a statistical measure of both the direction and the strength of a relationship between two variables?
A) a correlation coefficient
B) the descriptive method
C) an operational definition
D) a theory

Accepted Answer

A correlation coefficient is a statistical measure that combines the direction and strength of a relationship between two variables. The other options listed are not specific statistical measures of relationships between variables.

Question 20

A normal curve would approximate the distribution of
A) males and females in the total American population.
B) American children enrolled in each of the first through sixth grades.
C) the physical heights of all American women.
D) all of these data.

Accepted Answer

A normal curve is often used to approximate the distribution of continuous variables, such as height, weight, or IQ, in a population. Choice A includes both a binary variable (male or female) and a continuous variable (height, weight, etc.), so it would not be appropriate to describe the entire population as following a normal curve. Choice B is also not appropriate because the distribution of age among enrolled children in each grade would likely not form a smooth, symmetrical curve. Choice C, however, describes a continuous variable that is well-known to follow a roughly normal distribution in the population of American women.

Quiz 16: Statistical Reasoning in Everyday Life

Correlation is a measure of the extent to which two variables

When we ask,for example,how closely related are the personality scores of identical twins,we are asking how strongly two ________ are related.

To determine whether the strength of people's self-esteem is related to their income levels,researchers would most likely make use of

If a set of standardized test scores is normally distributed,having a mean of 50 and a standard deviation of 10,approximately 68 percent of the group members receive scores somewhere between

If IQ scores are normally distributed,having a mean of 100 and a standard deviation of 15,approximately what percentage of people have IQ scores somewhere between 70 and 130?

An inverse relationship in which scores for one variable increase as scores for another variable decrease represents

Correlational research is most useful for purposes of

A graphed cluster of dots,each of which represents the values of two factors,is called a

Approximately what percentage of the cases represented by the normal curve fall between ‒3 and +3 standard deviations from the mean?

A direct relationship in which two sets of scores increase together or decrease together represents

The symmetrical bell‑shaped figure used to represent the distribution of many physical and psychological characteristics is called a

To discover the extent to which economic status can be used to predict political preferences,researchers are most likely to use

The standard deviation is the square root of the average squared deviation of scores from the

Evelyn wants to know how consistent her bowling scores have been during the past season.Which of the following measures would tell her what she wants to know?

Approximately what percentage of the cases represented by the normal curve fall between -1 and +1 standard deviations from the mean?

Displaying data in a scatterplot can help us see the extent to which two variables are

Approximately 95 percent of the cases represented by the normal curve fall within ________ standard deviation(s) from the mean.

Which of the following is a statistical measure of both the direction and the strength of a relationship between two variables?

A normal curve would approximate the distribution of