Chapter 3: A Statistics Refresher

Statistical tools are used for
1. describing numbers
2. making inferences about numbers
3. drawing conclusions about numbers
4. all are correct
If you measured the number of children in each family in your research, which type of scale would you be using?
1. continuous
2. discrete
3. interval
4. none are correct
Which is the most common type of scale used in psychological tests?
1. continuous
2. discrete
3. ratio
4. none are correct
The type of scaling exemplified in the measurement of temperature with a Fahrenheit thermometer is:
1. continuous
2. discrete
3. ratio
4. interal
Frequency distributions of test scores are frequently illustrated by which kind of graph?
1. histogram
2. scatterplot
3. pie chart
4. bar graph
In a grouped frequency distribution,
1. the total of the frequency column is equal to the total number of scores in the distribution
2. test-score intervals replace the actual test scores
3. each test score must fall in only one test-score interval
4. all are correct
You administer a 100-item achievement test to 20 students in which students earn 1 point for each correct answer. You note one extreme score of 95. All the other students score between 20 and 30. What measure of central tendency would be most advisable to use?
1. average deviation
2. the median
3. the mode
4. the standard deviation
What is the formula for the arithmetic mean computed from a frequency distribution?
1. “summation of fx” divided by N
2. “summation of the absolute deviations” divided by N
3. “summation of x” divided by N
4. none are correct
When graphing ratio data, why is it preferable to set the ordinate of the y-axis at 0?
1. it is the traditional way of doing it but it has no inherent benefit
2. setting the ordinate to other values may give an exaggerated impression of the changes in the variable
3. doing so prevents people from questioning your data and conclusions
4. it is more exciting to the reader
T score is to 50 as:
1. z score is to 10
2. percentile is to 100
3. stanine is to 5
4. stanine is to 9
If a distribution of scores has a few extremely low scores and no corresponding high scores, which of the following would be true?
1. The mean would be smaller than the median
2. The mean would be larger than the median
3. The mean and the median would be equal
4. None are true—cannot be determined based on information presented
If the standard deviation of a set of test scores is equal to 5, the variance is equal to:
1. 25
2. 5
3. 50
4. 2.5
If the results of an examination are positively skewed, the exam questions were likely:
1. easy
2. difficult
3. biased
4. It is impossible to know
Arithmetic mean is to ________ as median is to ________.
1. semi-interquartile range; standard deviation
2. standard deviation; semi-interquartile range
3. variance; standard deviation
4. dispersion; variance
Which of the following is TRUE of kurtosis?
1. Computer programs provide an index of skewness between –2 and +3
2. Computer program provide an index of skewness between –1 and +1
3. Measurement specialists have not agreed on the measurement and interpretation of this concept
4. none are true
For a hypothetical distribution of “Citywide Math Test” scores with a mean of 70 and a standard deviation of 12, a score equal to 2 standard deviations above the mean would be:
1. 72
2. 82
3. 84
4. 94
Approximately what percentage of scores in a normal distribution falls between the mean and 1 standard deviation above and below the mean?
1. 34%
2. 68%
3. 95%
4. none are correct
A raw score of 82 coming from a distribution of scores with a mean of 76 and a standard deviation of 4 is equal to a z score of which of the following?
1. -1.5
2. 1.5
3. 4
4. -2
What is an advantage of T scores over z scores?
1. z scores have no negative numbers
2. T scores have no negative numbers
3. T scores are more precise
4. all are correct
What is the primary advantage of normalization of a skewed distribution?
1. greater validity
2. easier comparability to other scales
3. greater reliability
4. eliminates negative numbers
The amount of time that passes between the presentation of a word on a computer screen and the reading of a word by a test taker involves measurement on which type of scale?
1. ordinal
2. ratio
3. interval
4. nominal
Psychological assessment instruments often employ an ordinal scale because:
1. it can quantify categories such as ethnicity, sex, and medical diagnoses
2. it contains equal intervals between numbers
3. it has an absolute zero point
4. it permits rank-ordering of scores
Intelligence test scores are required as interval-level measurement, in part because:
1. the derived scores do not result from equal intervals
2. the scores represent a precise unit of measurement
3. it is not possible to receive a score of zero
4. a score of zero does not represent an absence of intelligence
If the mean of a distribution is 7 and the standard deviation is 2, what is the z score that is equivalent to a raw score of 3?
1. 2
2. -2
3. 3
4. -6
John received a z score of 0.5 on an exam. Peter received a T score of 60. What can we say about their relative performance on the exam?
1. There is not enough information to compare John's and Peter's exam scores
2. Peter received a higher raw score than John on the exam
3. John received a higher raw score than Peter on the exam
4. The two test takers actually received the same score on the exam

Chapter 3: A Statistics Refresher

Quiz