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| Describing Data: Measures of Variability
Multiple Choice
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| | 1 .
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| An instructor gave students a 20-item quiz on a course topic. The distribution of scores on the quiz was: 8, 8, 10, 10, 11, 12, 12, 13, 13, 13 15, 15, 16, 17, 19, 19, 20, 20, 20. What is the range for these scores? [Hint]
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| 20.
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| 12.
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| 16.
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| A range cannot be calculated for this set of scores.
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| | 2 .
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| The _____ for a set of scores can be obtained by using the formula X75 – X25. [Hint]
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| range
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| semi-interquartile range
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| interquartile range
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| median
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| | 3 .
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| The SIQR provides a measure of the average spread of scores for _____ of the scores above and below the [Hint]
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| 25 percent; median.
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| 75 percent; median
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| 25 percent; mean.
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| all; median.
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| | 4 .
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| The symbol for the sample variance is [Hint]
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| | 5 .
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| The sample variance is given by the formula [Hint]
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| | 6 .
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| _____ is the symbol for the population variance. [Hint]
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| | 7 .
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| For the set of three scores, 3, 6, 9, S2 is [Hint]
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| | 8 .
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| For the set of three scores, 3, 6, 9, s2 is [Hint]
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| | 9 .
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| Suppose thatis 7 for a population of scores. The variance for those scores is then [Hint]
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| | 10 .
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| The SS for a set of scores is 80 based on a sample of size 21. Thus, s2 for the scores is [Hint]
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| | 11 .
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| If s2 for a set of scores is 81, then s for those scores [Hint]
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| is 3.
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| is 9.
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| is (81)2.
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| cannot be determined from the information given.
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| | 12 .
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| Which of the following sets of scores would you expect to have the largest value of s? [Hint]
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| 5, 5, 6, 7, 7.
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| 7, 7, 7, 7, 7.
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| 5, 6, 7, 8, 9.
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| 5, 5, 7, 9, 9.
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| | 13 .
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| If s = 0 for a distribution of scores, then which of the following is true? [Hint]
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| An error was made in the calculation because s cannot equal 0.
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| All the scores in the distribution are equal to each other.
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| The sample variance of the scores was equal to 10.
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| The distribution was either positively or negatively skewed.
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| | 14 .
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| In journal articles following the Publication Manual of the American Psychological Association style, the standard deviation is usually represented by [Hint]
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| | 15 .
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| You have collected a set of scores from participants performing a reaction time task. You decide that the most appropriate measure of central tendency for the scores is the median. The most appropriate measures of variability would thus be the [Hint]
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| standard deviation.
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| sample variance.
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| SIQR.
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| range.
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What does variability refer to in a distribution of scores?
Variability refers to how spread scores are in a distribution out; that is, it refers to the amount of spread of the scores around the mean. For example, distributions with the same mean can have different amounts of variability or dispersion.
Which one of the following is best used to measure variability of scores?
Since the range only uses the largest and smallest values, it is greatly affected by extreme values, that is - it is not resistant to change. That's why the best measure of variability is standard deviation.
Which of the following is a measure of the variability of a distribution?
Standard error and standard deviation are both measures of variability. The standard deviation reflects variability within a sample, while the standard error estimates the variability across samples of a population.
What are the 4 measures of variability?
There are four frequently used measures of variability: the range, interquartile range, variance, and standard deviation.