# quiz1_answers-1 - -Econ*2740 W2012 Quiz 1a ECON*2740...

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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 swer- m-“m il HI Question “I- Answer :- l i ﬁrs—- '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 unit-free 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 right-skewed is positive if the distribution is right-skewed 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 unit-free? 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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