Dr. Hallam 3/13/15 Statistics Spring - 2015 Exam #2a Please print your name on the space provide below. There are 110 points on this...
anhnamDr. Hallam 3/13/15
Statistics
Spring - 2015
Exam #2a
Please print your name on the space provide below. There are 110 points on this exam (60 pts multiple choice and 50 points short answer). Be sure to answer all multiple choice questions as there is no penalty for guessing.
Name ______________________________________.
Multiple choice questions 1-20 are three points each. Circle the letter corresponding to the best answer.
1. A researcher records the weights of children by comparing their weight to the average for their age. Specifically, a score is obtained by taking the child’s weight and subtracting the average. Given an average weight of 105, original weights of 95, 110 and 100 become -10, +5 and -5. In this example weight’s are now measured on a ___________ scale.
A. nominal
B. ordinal
C. interval
D. ratio
2. Evaluate the following two statements: a) cumulative frequency refers to sum of all scores; b) a distribution can have more than one median.
A. a and b are both true
B. a is true and b is false
C. a is false and b is true
D. a and b are both false
3. The peak of a frequency distribution is always equal to the ___________.
A. mean
B. median
C. mode
D. all of the above
4. The ___________ is a midpoint in that the sum of the distances above it and below it are equal (the sum of the deviations from it are zero).
A. mean
B. median
C. mode
D. all of the above
5. Evaluate the following two statements: a) samples consistently tend to be more variable than their populations; b) degrees of freedom equals the sample size.
A. a and b are both true
B. a is true and b is false
C. a is false and b is true
D. a and b are both false
6. Evaluate the following two statements: a) samples tend to underestimate their populations with respect to variability; b) in many journals including those following APA style the symbol SD is used for the sample standard deviation.
A. a and b are both true
B. a is true and b is false
C. a is false and b is true
D. a and b are both false
7. The _________ and the __________ are the most common values used to describe a set of data.
A. mean / standard deviation
B. mean / median
C. mean / variance
D. median / variance
8. What is probability of obtaining three heads in a row on a fair coin fairly tossed ?
A. .0625
B. .25
C. .125
D. .35
9. Evaluate the following two statements: a) if every score in a distribution is added by some constant, then the standard deviation will stay the same; b) if every score in a distribution is subtracted by some constant, then the standard deviation will become smaller.
A. a and b are both true
B. a is true and b is false
C. a is false and b is true
D. a and b are both false
10. Evaluate the following two statements: a) the value you obtain for SS will be different depending on whether the set of scores is a sample or a population; b) variance is the mean of the squared deviation scores.
A. a and b are both true
B. a is true and b is false
C. a is false and b is true
D. a and b are both false
11. For a Z = 2.00 column B = .9772 and column C = .0228. For Z = 1.00 column B = .8413 and column C = .1587. The probability of obtaining a Z score above +2.00 or below -1.00 is ______________.
A. 0.8185
B. 0.1815
C. 0.1359
D. 0.6826
12. Evaluate the following two statements: a) a positive z-score will always correspond to a score more than the mean; b) for a positively skewed distribution a z-score of zero will be located to the left of the mean.
A. a and b are both true
B. a is true and b is false
C. a is false and b is true
D. a and b are both false
13. For a Z = 2.00 column B = .9772 and column C = .0228. For Z = 1.00 column B = .8413 and column C = .1587. The probability of obtaining a Z score between +2.00 and -1.00 is ______________.
A. 0.8185
B. 0.1815
C. 0.1359
D. 1.1359
14. _____________ is the average squared distance from the mean.
A. The sums of squares
B. The semi-interquartile range
C. Variance
D. Standard Deviation
15. __________ is the distance between the upper real limits of the largest X and lower real limits of the smallest X in the distribution.
A. The range
B. The semi-interquartile range
C. Variance
D. Standard deviation
16. Which of the following variability measures are based on the concept of a deviation?
A. range and semi-interquartile range
B. semi-interquartile range and variance
C. variance and standard deviation
D. standard deviation and range
17. Of the measures of variability ________________ is the most affected by extreme scores.
A. the range
B. the semi-interquartile range
C. variance
D. standard Deviation
18. When a distribution is open-ended the best measure of variability to use is ______________.
A. the range
B. the semi-interquartile range
C. variance
D. standard deviation
19. For a Z = 2.00 column B = .9772 and column C = .0228. For Z = 1.00 column B = .8413 and column C = .1587. The probability of obtaining a Z score between -2.00 and -1.00 is ______________.
A. 0.8185
B. 0.1815
C. 0.1359
D. 0.6826
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