15 Jan Question 47 Some information about

DATA205 Introductory Analytics (QC)

Exam 1

Question 1A discrete variable cannot be

Answers:

a. subdivided.

b. multiplied.

c. added.

d. observed.

Question 2A researcher has numbered all 50 states from 1 to 50 and has calculated a mean of 17.43 for the variable “state of birth.”

Answers:

a. Since the variable is ordinal, we should treat the value of the mean with great caution.

b. Since the variable is nominal, the mean makes no sense.

c. Since this variable is discrete, the mean should not be computed.

d. The variable is interval-ratio and the mean is an appropriate and useful statistic in this case.

Question 3A theory differs from an hypothesis in that it is more

Answers:

a. testable.

b. general.

c. concrete.

d. specific.

Question 4According to the “Wheel of Science,” research projects begin

Answers:

a. with data.

b. at any stage on the Wheel.

c. with an hypothesis.

d. with theory.

Question 5Addition and subtraction are completely justified only when variables are

Answers:

a. discrete.

b. continuous.

c. ordinal.

d. interval-ratio.

Question 6An hypothesis states, in part, that “income increases as education increases”. In this statement, income is

Answers:

a. the hypothetical variable.

b. the independent variable.

c. the dependent variable.

d. the secondary variable.

Question 7Choose the nominal level variable below:

Answers:

a. size of family unit

b. speed of travel of a jet

c. eye color of students in statistics class

d. your weight

Question 8In social research the purpose of statistics is to

Answers:

a. prove that the research theory is correct.

b. validate the research project design.

c. manipulate and analyze data.

d. ensure acceptance by the scientific community.

Question 9The data reduction process of descriptive statistics

Selected Answer:

a. allows a few meaningful numbers to summarize a large amount of data.

b. is rarely used.

c. eliminates incorrect data.

d. simply lists all available information in order.

Question 10 Which of the following is a discrete variable?

Answers:

a. Miles per gallon

b. Height

c. Number of children

d. Age

Question 11 Without statistics, _____________ research would be impossible.

Answers:

a. meaningful

b. qualitative

c. important

d. quantitative

Question 12A city of 1567 people had 34 auto thefts last year. The auto theft rate for this city

Answers:

a. is (34/1567) x 100,000.

b. is (100,000 x 1567)/34.

c. is falling.

d. cannot be determined from the information given.

Question 13A researcher wants to visually display the U.S. divorce rate (a continuous, interval-ratio level variable) for the last 50 years. An appropriate format would be

Answers:

a. a line chart or histogram.

b. only a histogram.

c. a pie chart.

d. none of the above. Data in the form of rate should never be displayed in a chart or graph.

Question 14For a single variable measured at the nominal level, an appropriate graph would be a

Answers:

a. bivariate table

b. frequency polygon.

c. histogram.

d. pie chart.

Question 15Frequency distributions may be compiled for variables measured at which level?

Answers:

a. Nominal

b. Ordinal

c. Interval-ratio

d. All of the above

Question 16Pie charts show the frequency distribution of

Answers:

a. one variable.

b. two variables.

c. three or more variables.

d. Any of the above

Question 17The sum of the proportions for all categories of a variable will be

Answers:

a. 0.10

b. 1.00

c. 10.00

d. 100.00

Question 18To be converted to a percentage, the proportion must be multiplied by

Answers:

a. 10.

b. 100.

c. 1000.

d. Any of the above

Question 19When working with a very small number of cases, it is usually preferable to report

Answers:

a. fractions.

b. actual frequencies.

c. proportions.

d. percentages.

Question 20Which of the following is an impossible value for a percentage?

Answers:

a. 0.0%

b. 110.00%

c. 0.05%

d. 47.458923%

Question 21A researcher is preparing a report and wants to select a measure of central tendency that shows the most common score in a particular distribution. Which statistic should she select?

Answers:

a. Mode

b. Median

c. Mean

d. None of the above

Question 22An instructor is preparing a report showing mid-semester grades and notes that the mean, median, and mode are all exactly 76.00. What can she conclude?

Answers:

a. The distribution of grades is unskewed.

b. There is a negative skew in the distribution (a few students have very low grades.)

c. There is a positive skew in the distribution (a few students have very high grades.)

d. All of the above

Question 23As a measure of central tendency, the mode can be used with?

Answers:

a. ?interval-ratio data.

b. ?all of these choices are correct.

c. ?ordinal data.

d. ?nominal data.

Question 24For ordinal level variables, the most appropriate measure of central tendency is generally

Answers:

a. the mode.

b. the median.

c. the mean.

d. None of the above

Question 25If a distribution of test scores has a mean of 70 and a median of 80, the distribution has

Answers:

a. a positive skew.

b. a mode of 75.

c. a few very high scores.

d. a negative skew.

Question 26If you changed ONLY the highest score in a distribution of 5 scores, which of the following measure of central tendency would be affected?

Answers:

a. The mean

b. The median

c. The mode

d. All of the above

Question 27The expression ?(Xi) directs us to find the

Answers:

a. average of the scores.

b. median.

c. middle score.

d. sum of the scores.

Question 28The three commonly used measures of central tendency (mode, median, and mean)

Answers:

a. define “typical” or “average” in different ways and will usually have different values.

b.will always fall in the same order: the mean will have the lowest value, the median will always be in the middle and the mode will have the highest value.

c. will always have the same value.

d. will always fall in the same order: the mean will have the highest value, followed by the median and the mode.

Question 29Which measure of central tendency is affected by every score in the distribution?

Answers:

a. The mean

b. The median

c. The mode

d. All of the above

Question 30Which of the following correctly matches the level of measurement of a variable with the preferred measure of central tendency?

Answers:

a. ordinal … mode

b. ordinal … median

c. interval-ratio … mode

d. nominal … mean

Question 31An advantage of the interquartile range (Q) over the range (R) is that it

Answers:

a. includes the most extreme scores.

b. is based on only the middle 50% of the scores.

c. can be used for nominal level variables.

d. ignores the first and third quartiles.

Question 32As a distribution of scores becomes more variable, the value of the standard deviation

Answers:

a. decreases.

b. increases.

c. becomes unpredictable.

d. stays the same.

Question 33If a distribution of scores has a mean of 30 and a range of 0

Answers:

a. the quartile deviation (Q) is 10.

b. there is no dispersion in the distribution.

c. the standard deviation is 1.

d. the variance is 30.

Question 34If a test score lies at the first quartile, it is

Answers:

a. the same as the median.

b. higher than 75% of the scores.

c. higher than 25% of the scores.

d. the same as the mode.

Question 35 If male and female college students have the same mean GPA but the standard deviation for females is much larger, you may conclude that

Answers:

a. median GPAs for both groups would be the same.

b. there is more variability among female students with respect to GPA.

c. males are smarter than females.

d. modal GPAs for both groups would be the same.

Question 36 Measures of dispersion provide information about the

Answers:

a. adequacy of the selection criteria for the sample.

b. variety within the distribution of scores.

c. typical or most common score.

d. size of the sample.

Question 37 One problem with the range (R) as a measure of dispersion is that it

Answers:

a. ignores the most extreme scores.

b. is very difficult to calculate.

c. can be used only for nominal level variables.

d. is based on only the most extreme scores.

Question 38 The expression ? instructs us to

Answers:

a. sum the scores and then subtract the mean.

b. sum the scores.

c. subtract the mean from each score and add up the deviations.

d. subtract every “ith” score from the mean.

Question 39 The lower limit for the standard deviation is 0; the upper limit is

Answers:

a. the score of the median.

b. a function of the number of cases.

c. undefined; there is no upper limit.

d. the score of the mean.

Question 40 The second quartile (Q2) is equal in value to

Answers:

a. the range.

b. the mode.

c. the mean.

d. the median.

Question 41What is the difference between a population and a sample?

Question 42 Below are some items from a survey. For each item, identify the level of measurement and whether the variable will be discrete or continuous.

a. In what region of the country were you born?

__ South

__ Northeast

__ Midwest

__ Far West

__ Other

__ Born out of Country

b. How many siblings do you have? ___

c. How satisfied are you with the quality of instruction at this institution?

__ Very satisfied

__ Satisfied

__ Dissatisfied

__ Very Dissatisfied

d. How many miles per gallon does your car average?_____

e. People convicted of first degree murder should be executed.

__ Strongly Agree

__ Agree

__ Neither Agree nor Disagree

__ Disagree

__ Strongly Disagree

Question 43 In 2005, a study in Smalltown USA reported a crime rate of 204 crimes for every 100,000 residents. A recent report from Smalltown USA’s local newspaper indicates the crime rate in 2015 was 81 crimes per 10,000 residents.

The mayor wants to hold a press conference to publicly celebrate the accomplishments of the police force over the last 10+ years. Would you agree with the mayor’s assertion that the city is safer now than it was 10 years ago?

BRIEFLY explain why or why not. (HINT: no extra calculations needed to answer this problem)

Question 44 Below is a boxplot for data gathered on Infant Mortality Rates from 70 different countries around the world

Based on the provided boxplot, what can you say about the distribution of these data?

Question 45 You are the Dean of students at a college and the President has asked for some information about how the student body has changed over the years. You have collected the following information regarding the number of students in various categories for two different graduating classes:

CHARACTERISTICS OF TWO GRADUATING CLASSES

1990 2010

Total in class 345 687

Females 178 301

Married 48 117

Humanities Majors 115 258

Going to Graduate School 78 159

Attended Commencement 99 458

Finished in 4 years 269 325

Received financial aid 159 369

What will you say to the president when she asks:

a. What percentage of the glass was going to graduate school in 2010? ______

b .Has this percentage gone up or down since 1990 and by how much? (Hint: Compute the percentage change to measure the amount of change between the two times)_____

c. What proportion of the class majored in the humanities in 1990?________ 2010?_______

Question 46 The frequency distribution below displays the distribution of age for a sample drawn from a community. Finish the table by completing the columns for percentages, and cumulative percentages.

AGE

Class Intervals Frequency Percentage Cumulative

Percentage

10 – 19 9

20 – 29 17

30 – 39 45

40 – 49 56

50 – 60 23

TOTALS

Question 47 Some information about auto theft rates (number of auto thefts per 100,000 population) for a sample of 178 cities in two different years is summarized below. Express this statistical information in words. What changes were there in the overall shape of the distribution of this variable? In central tendency? In dispersion?

1990 2010

Mean 150.32 125.17

Median 117.17 123.01

Standard Deviation 12.23 7.01