1The first raw moment of a distribution is equal to its:
Relation between raw moments and central moments
Easy
A.Variance
B.Mean
C.Skewness
D.Kurtosis
Correct Answer: Mean
Explanation:
The first raw moment is , which is the arithmetic mean.
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2What is the value of the first central moment ?
Relation between raw moments and central moments
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The first central moment is .
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3Which formula relates the second central moment to raw moments?
Relation between raw moments and central moments
Easy
A.
B., which squares the entire difference
C.
D.
Correct Answer:
Explanation:
Variance is the second central moment, given by .
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4Central moments are moments measured about the:
Relation between raw moments and central moments
Easy
A.Mean
B.Origin
C.Median
D.Mode
Correct Answer: Mean
Explanation:
The th central moment is , so it is measured about the mean.
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5A change of origin has what effect on central moments?
Effect of change of origin and scale on moments
Easy
A.They change sign
B.They become zero
C.No effect
D.Every central moment increases by the amount used to shift the origin
Correct Answer: No effect
Explanation:
Central moments are unchanged by a shift of origin because both the values and their mean shift equally.
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6If , the variance of is:
Effect of change of origin and scale on moments
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Subtracting a constant changes the origin but does not change the variance.
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7If , how is the second central moment transformed?
Effect of change of origin and scale on moments
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Under multiplication by , the th central moment is multiplied by .
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8For the transformation , the th central moment of is:
Effect of change of origin and scale on moments
Easy
A.
B., including the origin correction
C.
D.
Correct Answer:
Explanation:
Changing origin has no effect on central moments, while division by divides the th moment by .
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9Pearson's moment coefficient is defined as:
Pearsonian coefficients
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The Pearsonian coefficient measures squared skewness and equals .
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10Pearson's coefficient is given by:
Pearsonian coefficients
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The coefficient is used to describe kurtosis.
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11The moment coefficient of skewness is:
Pearsonian coefficients
Easy
A., using the fourth central moment
B.
C.
D.
Correct Answer:
Explanation:
Standardized skewness is .
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12What is the relationship between and ?
Pearsonian coefficients
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , squaring it gives .
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13A perfectly symmetric distribution has a skewness of:
Measures of skewness
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
A perfectly symmetric distribution has no directional asymmetry, so its skewness is zero.
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14A positively skewed distribution generally has a longer tail on the:
Measures of skewness
Easy
A.Right side
B.Central part of the distribution around its arithmetic mean
C.Both sides
D.Left side
Correct Answer: Right side
Explanation:
Positive skewness indicates that the distribution extends farther toward larger values on the right.
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15Karl Pearson's first coefficient of skewness is:
Measures of skewness
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Pearson's first coefficient compares the mean and mode relative to the standard deviation.
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16Karl Pearson's second coefficient of skewness is:
Measures of skewness
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Pearson's second coefficient is .
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17Kurtosis primarily describes the:
Kurtosis
Easy
A.Direction of skewness
B.Peakedness and tail weight
C.Location of the mean
D.Exact difference between the largest and smallest observations
Correct Answer: Peakedness and tail weight
Explanation:
Kurtosis describes the shape of a distribution in terms of its peak and tail weight.
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18For a normal distribution, Pearson's kurtosis coefficient equals:
Kurtosis
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
A normal distribution is mesokurtic and has .
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19A distribution with is called:
Kurtosis
Easy
A.Mesokurtic
B.Platykurtic
C.Leptokurtic
D.Symmetric with no measurable fourth central moment
Correct Answer: Leptokurtic
Explanation:
A leptokurtic distribution has kurtosis greater than the normal-distribution value of .
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20The excess kurtosis is calculated as:
Kurtosis
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Excess kurtosis compares a distribution with the normal distribution by subtracting from .
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21The first two raw moments of a distribution about the origin are and . What is the second central moment ?
Relation between raw moments and central moments
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using , we get .
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22For a distribution, , , and . Find the third central moment.
Relation between raw moments and central moments
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using , we obtain .
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23A distribution has mean , variance , and third central moment . What is its third raw moment ?
Relation between raw moments and central moments
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , the result is .
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24The first four raw moments of a distribution are , , , and . Find the fourth central moment.
Relation between raw moments and central moments
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Use . This gives .
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25A variable has mean and variance . If , what are the mean and variance of ?
Effect of change of origin and scale on moments
Medium
A.Mean , variance
B.Mean , variance
C.Mean , variance
D.Mean , variance
Correct Answer: Mean , variance
Explanation:
The mean becomes , while the variance is divided by , giving .
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26The third central moment of is . If , what is the third central moment of ?
Effect of change of origin and scale on moments
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
A change of origin has no effect on central moments, while scaling by multiplies the third central moment by . Thus, .
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27For , the first two raw moments are and . If , find the second raw moment of .
Effect of change of origin and scale on moments
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , we get .
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28A variable has moment coefficient of skewness and coefficient of kurtosis . If , what are the corresponding coefficients for ?
Effect of change of origin and scale on moments
Medium
A.,
B.,
C.,
D.,
Correct Answer: ,
Explanation:
A negative scale reverses the sign of skewness, while kurtosis is unchanged by a linear change of origin and scale.
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29For a distribution, , , and . Find Pearson's moment coefficients and .
Pearsonian coefficients
Medium
A.,
B.,
C.,
D.,
Correct Answer: ,
Explanation:
Here, and .
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30A distribution has and a positive third central moment. What is its signed moment coefficient of skewness ?
Pearsonian coefficients
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , we have . The positive third moment determines the positive sign.
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31If Pearson's coefficient of kurtosis is , what are the excess kurtosis and the corresponding classification?
Pearsonian coefficients
Medium
A., leptokurtic
B., platykurtic
C., platykurtic
D., leptokurtic
Correct Answer: , platykurtic
Explanation:
Excess kurtosis is . A negative value indicates a platykurtic distribution.
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32A positively skewed distribution has variance and Pearson's coefficient . What is its third central moment?
Pearsonian coefficients
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
From , we get . Positive skewness gives .
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33A distribution has mean , mode , and standard deviation . Find Pearson's first coefficient of skewness.
Measures of skewness
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Pearson's first coefficient is .
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34The mean, median, and standard deviation of a distribution are , , and , respectively. Find Pearson's second coefficient of skewness.
Measures of skewness
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Pearson's second coefficient is .
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35For a distribution, , the median is , and . What is Bowley's coefficient of skewness?
Measures of skewness
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Bowley's coefficient is .
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36A distribution has open-ended extreme classes, making its mean and standard deviation unreliable. Which measure of skewness is most appropriate?
Measures of skewness
Medium
A.The third-moment coefficient
B.Bowley's quartile coefficient
C.Pearson's mean-mode coefficient
D.Pearson's mean-median coefficient
Correct Answer: Bowley's quartile coefficient
Explanation:
Bowley's coefficient uses quartiles and the median, so it is less affected by extreme values and open-ended classes.
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37A distribution has second central moment and fourth central moment . Find and classify the distribution.
Kurtosis
Medium
A., mesokurtic
B., leptokurtic
C., platykurtic
D., leptokurtic
Correct Answer: , leptokurtic
Explanation:
The coefficient is . Since , the distribution is leptokurtic.
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38Which pair correctly gives the coefficient of kurtosis and excess kurtosis of a normal distribution?
Kurtosis
Medium
A.,
B.,
C.,
D.,
Correct Answer: ,
Explanation:
For a normal distribution, . Therefore, its excess kurtosis is .
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39A distribution has variance and coefficient of kurtosis . What is its fourth central moment?
Kurtosis
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , we have .
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40A variable has excess kurtosis . If , what is the excess kurtosis and classification of ?
Kurtosis
Medium
A., leptokurtic
B., platykurtic
C., leptokurtic
D., mesokurtic
Correct Answer: , leptokurtic
Explanation:
Kurtosis is unchanged by a linear change of origin and scale. Thus, the excess remains , indicating a leptokurtic distribution.
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41The first four raw moments of about zero are , , , and . What is the fourth central moment ?
Relation between raw moments and central moments
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Use . Substitution gives .
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42A random variable has mean , variance , and third central moment . What is its third raw moment ?
Relation between raw moments and central moments
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , the value is .
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43The first four moments of about an arbitrary origin are , , , and . Determine the fourth moment about the mean.
Relation between raw moments and central moments
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Here .
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44A distribution has mean and central moments , , and . Find its fourth raw moment.
Relation between raw moments and central moments
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Use . This gives .
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45Let , where and has nonzero variance. Which statement about moment-based shape coefficients is correct?
Effect of change of origin and scale on moments
Hard
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
Central moments transform as . A negative scale reverses signed skewness, while kurtosis and squared skewness remain unchanged.
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46For , suppose and . Which pair gives and ?
Effect of change of origin and scale on moments
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , and .
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47The first four raw moments of are , , , and . If , what is the fourth raw moment of ?
Effect of change of origin and scale on moments
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Expand : .
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48For the coded variable , the first three raw moments are , , and . What are ?
Effect of change of origin and scale on moments
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
For , and . Scaling by gives .
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49A distribution has Pearson's coefficient and a negative third central moment. What is its signed moment coefficient of skewness ?
Pearsonian coefficients
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Because , . The negative third central moment determines the negative sign.
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50A nondegenerate distribution has Pearsonian coefficient of skewness . What is the smallest theoretically possible value of ?
Pearsonian coefficients
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Pearson's moment inequality is . Hence .
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51For a nondegenerate random variable, when does equality hold in Pearson's inequality ?
Pearsonian coefficients
Hard
A.Exactly when the distribution is a symmetric three-point distribution
B.Exactly when the distribution has zero moment skewness
C.Exactly when the distribution is a nondegenerate two-point distribution
D.Exactly when the distribution belongs to the normal family
Correct Answer: Exactly when the distribution is a nondegenerate two-point distribution
Explanation:
Equality requires a quadratic function of the standardized variable to vanish almost surely, restricting the variable to two distinct support points.
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52A distribution has central moments , , and . Which tuple is correct?
Pearsonian coefficients
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
, , , and excess kurtosis is .
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53A distribution has , , and Bowley's coefficient of skewness equal to . What is the median ?
Measures of skewness
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Bowley's coefficient is . Thus , giving .
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54A variable has mean , median , and standard deviation . If , what is Pearson's second coefficient of skewness for ?
Measures of skewness
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
For , the mean is , the median is , and the standard deviation is . Hence .
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55For a distribution, , , and . What is Kelly's coefficient of skewness?
Measures of skewness
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Kelly's coefficient is .
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56A distribution has mean , standard deviation , and Pearson's first coefficient of skewness . Assuming the empirical relation holds exactly, which pair gives the median and Pearson's second coefficient?
Measures of skewness
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The first coefficient gives the mode as . Thus , so the median is and .
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57Independent identically distributed variables have finite variance and kurtosis . If their standardized sum is , what is ?
Kurtosis
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The original excess kurtosis is . For a standardized sum of four IID variables it becomes , so .
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58Independent variables and have variances and , and excess kurtoses and , respectively. What is the excess kurtosis of ?
Kurtosis
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Independent fourth cumulants add. The excess is .
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59Independent variables and have variances and , with kurtoses and . What is the kurtosis of ?
Kurtosis
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Only has nonzero excess, equal to . The variance contributions are and , so the excess of is .
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60For a degenerate distribution concentrated at a single value, all central moments of positive order are zero. What is the mathematically appropriate conclusion about and ?
Kurtosis
Hard
A.Both coefficients are one because the distribution has one support point
B.Both coefficients are zero because all central moments vanish
C. is zero while is three by continuity
D.Both coefficients are undefined because their denominators contain zero variance
Correct Answer: Both coefficients are undefined because their denominators contain zero variance
Explanation:
The definitions and become when , so neither coefficient is defined.
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