Behavioral Stats Ch 4
As variability within groups increases, the one observed mean difference is less a) apparent. b) stable. c) likely to be viewed as real. d) all of the above.
D
Among measures of variability, the standard deviation occupies the same position as does a) the mean among measures of central tendency. b) the variance. c) each of the remaining measures, such as the range and mean deviation. d) any other measure in statistics.
A
An electronics firm gives a $2,500 bonus to every salaried employee at the end of the year. Compared to the original distribution of salaries (without the bonus), the new distribution has a) a new mean and the same standard deviation. b) a new mean and a new standard deviation. c) the same mean and the same standard deviation d) the same mean and a new standard deviation.
A
Compared to the standard deviation for the distribution of salaries for all new college graduates, the standard deviation for the distribution of salaries for all new electrical engineers should be a) smaller. b) the same. c) larger. d) different.
A
Even though there are n deviations in a sample, only n 1 of these deviations supply a true picture of the population deviations because only n 1 are free to vary, given that the sum of a) n deviations from their own sample mean always equals zero. b) n deviations from their own population mean always equals zero. c) n 1 deviations from their own sample mean always equals zero. d) n 1 deviations from their own population mean always equals zero
A
If almost all of the staff of a psychology department can be classified as therapists, as opposed to researchers, variability of therapists and researchers within the department can be described as a) minimum. b) intermediate. c) maximum. d) none of the above
A
If the distribution of ages for college students has a mean of 23.74 and a standard deviation of 3.19, the latter number (3.19) is expressed in units of a) years. b) squared years. c) nothing, since 3.19 is a pure number (without units). d) all of the above, depending on your perspective.
A
In the unlikely event that sample observations can be expressed as deviations about the population mean (rather than the customary sample mean), the number of degrees of freedom would be a) n b) n - 1 c) N d) N - 1
A
No useful measure of variability is produced by taking the mean of all deviations (both positive and negative) about the mean for the original observations because the resulting measure a) always equals zero. b) is the same as the mean of the original observations. c) exaggerates the variability in the distribution. d) is too difficult to interpret.
A
The value of the standard deviation most closely resembles that of the a) mean absolute deviation. b) range. c) variance. d) mean.
A
The variance can be described as the a) mean of the squared deviations. b) square of the mean deviation. c) mean deviation. d) deviation of the mean.
A
When calculating the sum of squares with the definition formula, each deviation is squared in order to a) eliminate negative signs from deviation scores. b) generate squared units of measurement. c) emphasize the contributions of larger deviations. d) attain all of the above.
A
. It's probably most helpful to think of the standard deviation as a) equal to the average deviation. b) a rough measure of the average deviation. c) closely related to the range. d) the most important measure of variability.
B
A key liability of the variance is that it a) reflects the contributions of all observations. b) generates squared units of measurement. c) remains unaffected by increases in the total number of observations. d) entails an extraordinary amount of computational labor.
B
A key property of the interquartile range is its a) sensitivity to all observations. b) resistance to the distorting effect of extreme observations. c) sensitivity to extreme observations. d) use of information from only two observations.
B
A survey reveals that the distribution of miles driven by American drivers each year has a mean of 11,000 miles and a standard deviation of 3,000 miles. This implies that a majority drive a) between 5,000 and 17,000 miles. b) between 8,000 and 14,000 miles. c) between 2,000 and 20,000 miles. d) more than 11,000 miles.
B
An attractive feature of the range is that it a) uses information from only two observations. b) can be easily understood. c) tends to increase with increases in the total number of observations. d) can be used with any data.
B
As variability within groups decreases, differences between group means become a) less detectable. b) more detectable. c) larger. d) smaller
B
Degrees of freedom refer to the number of values that are free to vary, given a) the range of possible values. b) one or more mathematical restrictions. c) that each value is independent of all other values. d) that all values contribute equally.
B
Indicate which one of the following sets of observations has the larger standard deviation. (Calculations aren't necessary to answer this question.) a) 4045, 4050, 4055 b) 5, 20, 35 c) 530, 540, 550 d) 988, 1000, 1012
B
The standard deviation, but not the mean, a) appears as a key component in other statistical expressions. b) describes deviation scores rather than original observations. c) reflects the contributions of all observations. d) measures important properties of frequency distributions.
B
When estimating the population standard deviation, always use the version of the sample standard deviation where a) deviation scores can be used. b) n 1 appears in the denominator. c) raw scores can be used. d) the sample mean appears.
B
A basic question is whether an observed mean difference between two groups should be viewed as a) relatively large or small. b) expected or unexpected. c) real or transitory. d) fixed or variable.
C
Appearing in the computation formula for the sum of squares, the expression ΣX² indicates that a) each deviation should be squared, then all squared deviations should be added. b) all deviations should be added, then the total should be squared. c) each score should be squared, than all squared scores should be added. d) all scores should be added, then the total should be squared.
C
If qualitative data can be ordered (ordinal measurement), it's appropriate to describe variability by a) calculating the standard deviation. b) determining the distance between extreme observations. c) identifying extreme observations. d) approximating the mean deviation.
C
Measures of variability for qualitative data are a) the same as for quantitative data. b) quite similar to those for quantitative data. c) virtually nonexistent. d) among the most informative.
C
The computation formula for the sum of squares is preferred whenever a) the number of observations is large. b) the mean equals some complex number. c) either a or b d) neither a nor b
C
The interquartile range is defined as the range for the middle a) 25% of all observations. b) 33% of all observations. c) 50% of all observations. d) 75% of all observations.
C
The interquartile range often is used with the a) mean. b) mode. c) median. d) all of the above
C
The standard deviation never can be a) zero. b) smaller than the mean. c) negative. d) larger than the mean absolute deviation.
C
Among frequency distributions for physical stamina scores, the greatest variability probably would occur in the distribution for a) well trained athletes. b) patients at a health clinic. c) infants. d) the general population.
D
Assume that an investment firm gives a 10 percent bonus to every salaried employee at the end of the year. Compared to the original distribution of salaries (without the bonus), the new distribution has a) the same mean and the same standard deviation. b) the same mean and a new standard deviation. c) a new mean and the same standard deviation. d) a new mean and a new standard deviation.
D
Compared to the definition formula, the computation formula for the sum of squares a) is algebraically equivalent. b) yields the same numerical value within rounding errors. c) often is computationally more efficient. d) possesses all of the above properties.
D
For most distributions,___________________ of all observations are within one standard deviation of the mean. a) a small minority b) a minority c) a large majority d) a majority
D
If a survey of grade-school children reveals that the distribution of daily TV-viewing times has a mean of 2.3 hours and a standard deviation of 1.0 hours, this implies that a) no child watches TV for fewer than 1.3 hours. b) some children watch TV for fewer than zero hours. c) every child watches TV for either 1.3, 2.3, or 3.3 hours. d) a majority of children watch TV between 1.3 and 3.3 hours.
D
If the distribution of weekly study times reported by college students has a mean of 25 hours with a standard deviation of 10 hours, this implies that a) a small minority study either less than 5 hours or more than 45 hours. b) a majority study between 15 and 35 hours. c) individuals deviate, on the average, approximately 10 hours from the mean of 25 hours. d) all of the above
D
Indicate which one of the following sets of observations each having a mean of 50 has the larger standard deviation. (Calculations aren't necessary to answer this question.) a) 40, 49, 50, 51, 60 b) 40, 45, 50, 55, 60 c) 40, 42, 50, 58, 60 d) 40, 40, 50, 60, 60
D
The mean and the standard deviation are a) both measures of position. b) both measures of distance. c) measures of distance and position, respectively. d) measures of position and distance, respectively.
D
The standard deviation can be described as a) a measure of variability. b) only a square root away from the variance. c) a measure that reflects the contributions of all observations. d) all of the above
D
When calculating the variance and standard deviation, you always must find the value of the a) mean. b) mean deviation. c) sum of the deviations. d) sum of squares
D