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Unformatted text preview: Econ*2740 W2012, Quiz 1a ECON*2740, Economic Statistics Quiz #1, Winter 2012  ID Number: Please enter you answers in the following grid —— get 2 points for doing so. There are 10
questions at 2 points each. Maximum score is 22. Points are awarded only for the most
appropriate answer ' Questibn 4
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'0 1. The standard deviation of the random variable X has the same units as X b has units equal to the" squared units of X
c. is the average deViation of X from its mean
(1 must be between 1 and +1 ' 2. Xi (i = 1,...250) is the price of items in a catalogue. If all 250 prices are increased
by $1.50 the standard deviation of X will. increase by the square root of $1.50
increase by $1.50
change by an amount that cannot be determined with this information a
b.
c. . remain unchanged ' ‘uI—L—uau  um Econ*2740 W2012, Quiz 1a X (i _=_ 1,...250) is the price of items in a catalogue. If all 250 prices are increased
by 5%, the standard deviation of X will I ' increase by a factor of (1.05)% increase by a factor of 1.05
change by an amount that cannot be determined with this information remain unchanged
The mean absolute deviation is another name for the standard deviation is a unitfree measure of dispersion is another name for variance is a meaSure of spread similar to but different from the standard deviation The distribution of the random variable X has a skewness coefﬁcient of +1, which
implies that the distribution is symmetric
the median of X exceeds the mean of X . more than 50% of the observations lie below the mean of X the variance of X is +1 In a sample of size n the sum of the deviations from the mean: Z’ﬂXi e X)
is negative if the distribution is rightskewed is positive if the distribution is rightskewed is positive if more than 50%‘of the observations lie above the mean of X is certainly 0 I Which of the following variables are unitfree? skewness and the coefﬁcient of variation ' the coefﬁcient of variation and the standard deviation the standard deviatibn and skewness . _
the standard deviation, skewness and the coefﬁcient of variation Econ*2740 W2012, Quiz 1a 8. c.
d. 99a?” 10. The inter—quartilerange of an ordered sample has 25% of the observations below its lower limit is the smallest interval that contains 50% of observations in the sample
is the largest interval that contains 50% of observations in the sample
is an interval that contains 25% of observations in the sample Consider a sample of wages measured in $ per hour. The numerical values of the
standard deviation and the mean are 2 and 10 respectively. The coefﬁcient of
variation is $0.2 per hour
0.2 5 $5 per hour Which of the following is/are true? the median is also the second quartile .
75% of observations in an ordered sample lie below the third quartile
25% of observations in an ordered sample lie below the ﬁrst quartile all of the above ...
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 Spring '12
 JONATHON
 Economics

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