Exam 1 Review
A class takes a 100-point midterm, and the results are: Class Y: 99, 97, 97, 94, 93, 90, 90, 88, 85, 81 If the score of 81 is changed to 31, what will happen to the median? A) It will remain the same. B) It will decrease, but by less than 1 point. C) It will decrease by 5 points. D) Cannot be determined from the information given.
A) It will remain the same.
Twenty students take a 10-point quiz, and John obtains a score of 7. At least eight students scored lower than 7. Given only this information, which of the following must be true? A) John's percentile rank cannot be lower than 40. B) John's percentile rank cannot be lower than 55. C) John cannot have received the highest score. D) John's percentile rank must be higher than 50.
A) John's percentile rank cannot be lower than 40.
The sum of the distances of all scores from the mean is: A) always equal to zero. B) always equal to 1.0. C) always equal to N. D) different for different groups of data.
A) always equal to zero.
Subjects are randomly assigned to watch either a horror movie or a comedy, and the amount of popcorn they eat during the movie is measured. For this experiment, the type of movie is: A) an independent variable. B) a dependent variable. C) a continuous variable. D) a constant.
A) an independent variable.
The purpose of inferential statistics is to: A) draw conclusions about a group that is too large to measure. B) summarize important characteristics of a set of data. C) draw inferences about the sample that the researcher is studying. D) none of the above.
A) draw conclusions about a group that is too large to measure.
A frequency distribution is unimodal if it: A) has only one peak. B) has at least two peaks. C) can be divided into two mirror-image halves. D) has a long "tail" at one end.
A) has only one peak.
A distribution can have more than one: A) mode. B) median. C) mean. D) mode, median, or mean.
A) mode.
A very easy exam would be likely to produce a distribution that is: A) negatively skewed. B) positively skewed. C) unimodal and symmetric. D) rectangular.
A) negatively skewed.
The purpose of a frequency distribution is: A) only descriptive—to conveniently summarize and describe large quantities of data. B) only inferential—to draw conclusions about a group that is too large to measure. C) either descriptive or inferential, depending on the goals of the researcher. D) neither descriptive nor inferential.
A) only descriptive—to conveniently summarize and describe large quantities of data.
The score at or below which a given percent of the cases fall is called a: A) percentile. B) percentile rank. C) transformed score. D) z score.
A) percentile.
Suppose that 10 people have exactly the same score. All of them received a score of 4.0. The variability of these 10 scores is: A) zero. B) 1.0. C) 4.0. D) Cannot be determined from the information given.
A) zero.
In a grouped frequency distribution, the lower real limit of the 24-26 interval is: A) 23.0 B) 23.5 C) 23.9 D) 24.0
B) 23.5
If ΣY = 22 and N = 5, is equal to: A) 0.2 B) 4.4 C) 22.0 D) cannot be determined from the information given
B) 4.4
On a midterm exam, your score expressed as a z score is -1.50. The mean of the exam is 70, and the standard deviation is 8. Your raw score is: A) 54. B) 58. C) 82. D) 86.
B) 58
A set of scores has a mean of 10.5 and a standard deviation of 3.5. If every score is divided by 5, what are the new mean and standard deviation? A) Mean = 2.1, standard deviation = 3.5 B) Mean = 2.1, standard deviation = 0.7 C) Mean = 10.5, standard deviation = 0.7 D) Mean = 10.5, standard deviation = 3.5
B) Mean = 2.1, standard deviation = 0.7
A distribution that is skewed to the right would have: A) a small number of very low scores. B) a small number of very high scores. C) both of the above. D) neither of the above.
B) a small number of very high scores.
The standard deviation and variance are measures of: A) the general location of a set of scores. B) how spread out the scores in a set of data are from one another. C) both of the above. D) neither of the above.
B) how spread out the scores in a set of data are from one another.
The percent of cases in a specific reference group scoring at or below a given score is called a: A) percentile. B) percentile rank. C) transformed score. D) z score.
B) percentile rank.
The purpose of descriptive statistics is to: A) draw conclusions about a group that is too large to measure. B) summarize important characteristics of a set of data. C) both of the above. D) neither of the above.
B) summarize important characteristics of a set of data.
In a positively skewed distribution: A) the mean is smaller than the median. B) the mean is larger than the median. C) the mean and the median are equal. D) none of the above.
B) the mean is larger than the median.
It is not possible for more than half of the scores in a distribution to be above: A) the mode. B) the median. C) the mean. D) the mode, median, or mean.
B) the median.
A decile divides the total number of cases into how many equal parts? A) 2 B) 4 C) 10 D) 100
C) 10
A class takes a 100-point midterm, and the results are: Class Y: 99, 97, 97, 94, 93, 90, 90, 88, 85, 81 If the score of 81 is changed to 31, what will happen to the mean? A) It will remain the same. B) It will decrease, but by less than 1 point. C) It will decrease by 5 points. D) Cannot be determined from the information given.
C) It will decrease by 5 points.
For which of the following sets of scores would a grouped frequency distribution be most appropriate? A) Set A: 79, 72, 81, 77, 84, 80, 83, 78, 77, 81 B) Set B: 1,083, 1,279, 406 C) Set C: 97, 46, 82, 65, 77, 89, 67, 58, 92, 87, 75, 74 73, 81, 87, 82, 75, 76, 84, 87, 92, 54, 62, 51, 88, 75, 73, 78, 80 D) Set D: 7, 10, 8, 5, 6, 12, 0, 4, 11, 7, 3, 5, 8, 6, 7, 2, 9, 8, 11, 10, 1, 11, 12, 7, 5, 3, 4, 6, 11, 10, 8, 7, 6, 5, 5, 3
C) Set C: 97, 46, 82, 65, 77, 89, 67, 58, 92, 87, 75, 74 73, 81, 87, 82, 75, 76, 84, 87, 92, 54, 62, 51, 88, 75, 73, 78, 80
Which of the following represents the highest score? A) The first quartile B) The fourth decile C) The median D) The 30th percentile
C) The median
As used in statistics, the term population refers to: A) only human beings, such as all American citizens. B) all of the numerical data collected by the researcher. C) a large group of people, cases, or responses that are alike in at least one respect. D) the group of people studied by the researcher.
C) a large group of people, cases, or responses that are alike in at least one respect.
A regular frequency polygon displays data by using: A) bars. B) cumulative frequencies. C) points on a graph that are connected. D) "stems" and "leaves."
C) points on a graph that are connected.
In a symmetric distribution: A) the mean is smaller than the median. B) the mean is larger than the median. C) the mean and the median are equal. D) none of the above.
C) the mean and the median are equal.
If the standard deviation of a set of scores is 4.0 and each score is multiplied by 3, what is the new variance? A) 4.0 B) 12.0 C) 27.0 D) 144.0
D) 144.0
A frequency distribution is skewed if it: A) has only one peak. B) has at least two peaks. C) can be divided into two mirror-image halves. D) has a long "tail" at one end.
D) has a long "tail" at one end.
One serious problem with grouped frequency distributions is that they: A) require a great deal of time and effort. B) do not look as neat and concise as regular frequency distributions. C) are not suitable for very large samples. D) lose information.
D) lose information.
The range is defined as: A) the average distance between each pair of scores. B) the average distance of each score from the mean. C) the largest distance of a score from the mean. D) the largest score minus the smallest score.
D) the largest score minus the smallest score.
If the same constant is subtracted from all of the scores in a distribution: A) the standard deviation will be negative. B) that constant will be subtracted from the standard deviation. C) that constant will be added to the standard deviation. D) the standard deviation will be unchanged.
D) the standard deviation will be unchanged.
