Descriptive Statistics

1. What is the median of the following set of scores?

18, 6, 12, 10, 14 ?

a. 10

b. 14

c. 18

d. 12

2. Approximately what percentage of scores fall within one standard deviation of the mean in a normal distribution?

a. 34%

b. 95%

c. 99%

d. 68%

3. The denominator (bottom) of the z-score formula is

a.      The standard deviation

b.     The difference between a score and the mean

c.      The range

d.     The mean

4. Let's suppose we are predicting score on a training posttest from number of years

of education and the score on an aptitude test given before training. Here is the regression

equation    Y = 25 + .5X₁ +10X₂,

where X₁ = years of education and X₂  = aptitude test score.

What is the

 predicted score for someone with 10 years of education and a aptitude test score of 5?

a. 25

b. 50

c. 35

d. 80

5. The standard deviation is:

a. The square root of the variance

b. A measure of variability

c. An approximate indicator of how numbers vary from the mean

d. All of the above

6. Hypothesis testing and estimation are both types of descriptive statistics.

a. True

b. False

7. A set of data organized in a participants(rows)-by-variables(columns) format is known as a “data set.”

a. True

b. False

8. A graph that uses vertical bars to represent data is called a ____.

a.  Line graph

b.  Bar graph

c.  Scatterplot

d.  Vertical graph

9. The goal of ___________ is to focus on summarizing and explaining a specific set of data.

a.  Inferential statistics

b.  Descriptive statistics

c.  None of the above

d.  All of the above

10. The most frequently occurring number in a set of values is called the ____.

a. Mean

b. Median

c. Mode

d. Range

11. As a general rule, the _______ is the best measure of central tendency because it is more precise.

a. Mean

b. Median

c. Mode

d. Range

12. Focusing on describing or explaining data versus going beyond immediate data and making inferences is the difference between _______.

a. Central tendency and common tendency

b. Mutually exclusive and mutually exhaustive properties

c. Descriptive and inferential

d. Positive skew and negative skew

13. Why are variance and standard deviation the most popular measures of variability?

a. They are the most stable and are foundations for more advanced statistical analysis

b. They are the most simple to calculate with large data sets

c. They provide nominally scaled data

d. None of the above

14. ____________ is the set of procedures used to explain or predict the values of a dependent variable based on the values of one or more independent variables.

a. Regression analysis

b. Regression coefficient

c. Regression equation

d. Regression line

15. The ______ is the value you calculate when you want the arithmetic average.

a.  Mean

b.  Median

c.  Mode

d.  All of the above

16. ___________ are used when you want to visually examine the relationship between two quantitative variables.

a. Bar graphs

b. Pie graphs

c. Line graphs

d. Scatterplots

17. The _______ is often the preferred measure of central tendency if the data are severely skewed.

a. Mean

b. Median

c. Mode

d. Range

18. Which of the following is the formula for range?

a.   H + L

b.   L x H

c.   L - H

d.   H – L

19. Which is a raw score that has been transformed into standard deviation units?

a.   z score

b.   SDU score

c.   t score

d.   e score

20. Which of the following is NOT a measure of variability?

a.  Median

b.  Variance

c.  Standard deviation

d.  Range

21. Which of the following is NOT a common measure of central tendency?

a.  Mode

b.  Range

c.  Median

d.  Mean

22. What is the median of this set of numbers: 4, 6, 7, 9, 2000000?

a. 7.5

b. 6

c. 7

d. 4

23. What is the mean of this set of numbers: 4, 6, 7, 9, 2000000?

a. 7.5

b. 400,005.2

c. 7

d. 4

24.  Which of the following  is interpreted as the percentage of scores in a reference group that falls below a particular raw score?

a.  Standard scores

b.  Percentile rank

c.  Reference group

d.  None of the above

25. The median is ______.

a.  The middle point

b.  The highest number

c.  The average

d.  Affected by extreme scores

26. Which measure of central tendency takes into account the magnitude of scores?

a. Mean

b. Median

c. Mode

d. Range

27. If a test was generally very easy, except for a few students who had very low scores, then the distribution of scores would be _____.

a. Positively skewed

b. Negatively skewed

c. Not skewed at all

d. Normal

28. How many dependent variables are used in multiple regression?

a. One

b. One or more

c. Two or more

d. Two

29. Which of the following represents the fiftieth percentile, or the middle point in a set of numbers arranged in order of magnitude?

a. Mode

b. Median

c. Mean

d. Variance

30. If a distribution is skewed to the left, then it is __________.

a. Negatively skewed

b. Positively skewed

c. Symmetrically skewed

d. Symmetrical

31. In a grouped frequency distribution, the intervals should be what?

a. Mutually exclusive

b. Exhaustive

c. Both A and B

d. Neither A nor B

32. When a set of numbers is heterogeneous, you can place more trust in the measure of central tendency as representing the typical person or unit.

a. True

b. False

33. Non-overlapping categories or intervals are known as ______.

a.       Inclusive

b.      Exhaustive

c.       Mutually exclusive

d.      Mutually exclusive and exhaustive

34. To interpret the relationship between two categorical variables, a contingency table should be constructed with either column or row percentages, and ----.

a. If the percentages are calculated down the columns, then comparisons should be made across

the rows

b. If the percentages are calculated across the rows, comparisons should be made down the

columns

c. Both a and b are correct

d. Neither a nor b is correct

Answers:

1. d

2. d

3. a

4. d

5. d

6. b

7. a

8. b

9. b

10. c

11. a

12. c

13. a

14. a

15. a

16. d

17. b

18. d

19. a

20. a

21. b

22. c

23. b

24. b

25. a

26. a

27. b

28. a

29. b

30, a

31. c

32. b

33. c

34. c