Note: It is recommended that you save your response as you complete each question.
Question 1 . Both ordinal and nominal variables are categorical.
True
False
Question 2. The time required to drive from Detroit to Lansing is an example of a discrete random variable.
True
False
Question 3. Phone numbers, Social Security numbers, and zip codes are examples of numerical variables.
True
False
Question 4. If you are in a class where most students do reasonably well on a test but a few pull down the class average, the histogram describing the test scores will indicate a positively-skewed distribution.
True
False
Question 5. Some histograms have two or more peaks. This is often an indication that the data come from two or more distinct populations.
True
False
Question 6. Statisticians often refer to the pivot tables as contingency tables or crosstabs.
True
False
Question 7 . The scatterplot is a graphical technique used to describe the relationship between two numerical variables.
True
False
Question 8. A variable (or field) is an attribute, or measurement, on members of a population, whereas an observation (or case or record) is a list of all variable values for a single member of a population.
True
False
Question 9 . A data sample has a mode of 140, a median of 130, and a mean of 120. The distribution of the data is positively skewed.
True
False
Question 10 . Suppose that a sample of 8 observations has a sample variance of 2.50, then the sum of the squared deviations from the sample mean is 17.50.
True
False
Question 11. If two data sets have the same range, the smallest and largest observations in both sets should be the same
True
False
Question 12 . The standard deviation is measured in original units, such as dollars and pounds.
True
False
Question 13. The median is one of the most frequently used measures of variability.
True
False
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Question 14. It is possible that the data points are close to a curve and have a correlation close to 0, because correlation is relevant only for measuring linear relationships.
True
False
Question 15. Numerical variables can be subdivided into which two types?
Diverse and categorical
Discrete and continuous
Nominal and progressive
Cross-sectional and discrete
Question 16. A sample of a population taken at one particular point in time is categorized as:
categorical
discrete
cross-sectional
time-series
Question 17. A scatterplot allows one to see:
whether there is any relationship between two variables
what type of relationship there is between two variables
Both (a) and (b) are correct
Neither (a) nor (b) is correct
Question 18 . A bimodal histogram is often an indication that the:
data are incorrect
data are inconclusive
sample is not representative of the population
data come from two or more distinct populations
Question 19. A population includes:
only people
only households
all objects of interest in a particular study
only machines
Question 20. Which of the following statements are false?
A categorical variable is nominal if there is natural ordering of its possible values.
A variable is numerical if meaningful arithmetic can be performed on it.
Zip codes are usually treated as categorical variables, although they appear to be numerical.
All of the above
Question 21. Which of the following are true statements of pivot tables?
They allow us to "slice and dice" data in a variety of ways.
Statisticians often refer to them as contingency tables or crosstabs.
Pivot tables can list counts, averages, sums, and other summary measures, whereas contingency tables list only counts.
All of the options.
Question 22. Which of the following are considered measures of association?
Mean and variance
Variance and correlation
Correlation and covariance
Covariance and variance
First quartile and third quartile
Question 23. The mode is best described as the
middle observation
same as the average
50th percentile
most frequently occurring value
third quartile
Question 24. Which of the following statistics is not a measure of central location?
Mean
Median
Mode
Interquartile range
Question 25. The correlation coefficient is always a value between
- 1 and 0
0 and +1
0.0 and 100
-1 and +1
-1 and 100
Question 26 . For a boxplot, the vertical line inside the box indicates the location of the
mean
median
mode
minimum value
maximum value
Question 27. For a boxplot, the box itself represents what percent of the observations?
lower 25%
middle 50%
upper 75%
upper 90%
100%
Question 28. Which of the following statements is true?
The sum of the deviations from the mean is always zero
The sum of the squared deviations from the mean is always zero
The range is always smaller than the variance
The standard deviation is always smaller than the variance
Question 29. A sample of 20 observations has a standard deviation of 4. The sum of the squared deviations from the sample mean is:
400
320
304
288
Question 30. A data set from a sample of 399 Michigan families was collected. The characteristics of the data include family size (large or small), number of cars owned by family (1, 2, 3, or 4), and whether family owns a foreign car. Excel produced the pivot table shown below.
Use this pivot table to determine how family size and number of cars owned influence the likelihood that a family owns a foreign car.
Question 31. A real estate agent has gathered information on 40 houses that were recently sold in a local community. The data she collected represent the following variables: the selling price of each house (in thousands of dollars), the appraised value of each house (in thousands of dollars), the size of the house (in hundreds of square feet), and the number of bedrooms.
Indicate whether each of the four variables is continuous or discrete.
Question 32. A recent survey data collected from 1000 randomly selected Internet users. The characteristics of the users include their gender, age, education, marital status and annual income. Using Excel, the following pivot tables were produced.
Approximate the percentage of these Internet users who are married with formal education beyond high school.
Question 33. A recent survey data collected from 1000 randomly selected Internet users. The characteristics of the users include their gender, age, education, marital status and annual income. Using Excel, the following pivot tables were produced.
Approximate the percentage of these Internet users who are in the 58-71 age group.
Question 34. The histogram below represents scores achieved by 250 job applicants on a personality profile.
Sixty percent of the job applicants scored below what value?
Question 35. The histogram below represents scores achieved by 250 job applicants on a personality profile.
How many job applicants scored between 10 and 30?
Question 36. A manager for Marko Manufacturing, Inc. has recently been hearing some complaints that women are being paid less than men for the same type of work in one of their manufacturing plants. The boxplots shown below represent the annual salaries for all salaried workers in that facility (40 men and 34 women).
Would you conclude that there is a difference between the salaries of women and men in this plant? Justify your answer.
Question 37. A statistics professor has just given a final examination in his statistical inference course. He is particularly interested in learning how his class of 40 students performed on this exam. The scores are shown below.
77 81 74 77 79 73 80 85 86 73
83 84 81 73 75 91 76 77 95 76
90 85 92 84 81 64 75 90 78 78
82 78 86 86 82 70 76 78 72 93
What are the mean and median scores on this exam? Explain why the mean and median are different.
Question 38. An economic development researcher wants to understand the relationship between the average monthly expenditure on utilities for households in a particular middle-class neighborhood and each of the following household variables: family size, approximate location of the household within the neighborhood, and indication of whether those surveyed owned or rented their home, gross annual income of the first household wage earner, gross annual income of the second household wage earner (if applicable), size of the monthly home mortgage or rent payment, and the total indebtedness (excluding the value of a home mortgage) of the household.
The correlation for each pairing of variables is shown in the table below:
Table of correlations
Which of the variables appears to have the weakest linear relationship with the household's average monthly expenditure on utilities?
Question 39. The following data represent the number of children in a sample of 10 families from Chicago: 4, 2, 1, 1, 5, 3, 0, 1, 0, and 2.
• Compute the mean number of children.
• Compute the median number of children.
• Is the distribution of the number of children symmetrical or skewed? Why?