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ECN225-EXAM1 FURMAN ROE

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Question
Answer
Compare a 'population' to a 'sample'.   Pop = set of all measurements of interestSample = subset of the population  
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Compare a 'parameter' to a 'statistic'.   Parameter = a # deduced from the populationStatistic = a # taken from the sample data  
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What is the problem with populations/parameters? Or, why do we use samples/statistics more frequently?   Populations and parameters are very difficult to gather. Stats gives us an accurate account of the larger groups information.  
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Define 'mean'.   The sum of the observations divided by the # of observations. (average)  
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Define 'median'.   The value in the middle of the data set when they are organized lowest to highest. This is averaged when there are two numbers. (middle)  
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Define 'mode'.   The value that occurs with the greatest frequency.  
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Define and calculate a 'percentile'.   Def - The pth percentile is a value where p percent of all observations are less than or equal to this value. i = (p/100)n, where n is the number of values. 'i' is the i'th number in the ordered list of data. note: the 50th percentile is also the median.  
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Calculate the 'quartiles'.   Q1 :: i=(25/100)n , Q2 :: i=(50/100)n , Q3 :: i=(75/100)n  
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Calculate 'range'.   largest value - smallest value = range  
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Calculate 'Interquartile Range (IQR)'.   IQR = [Q1 - Q3] , Q1 :: i=(25/100)n , Q3 :: i=(75/100)n  
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Define the 'variance' and calculate sample variance.   The measure of variability around the mean. Sample variance (denoted as s^2) = (sum of all squared deviations)/(n - 1) where "deviations" is (x'i - mean)  
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Define and calculate the 'standard deviation'.   The standard deviation is the positive square root of the variance.  
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Calculate the 'coefficient of variation'.   ((standard deviation / mean) x 100)%  
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Define and calculate the 'z-score'.   aka 'the standardized value'. The number of standard deviations the value is away from the mean. (x'i - mean)/(sample standard deviation)  
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Define 'Chebyshev's Theorem'.   At least (1 - 1/z^2) of the data values must be within z standard deviations of the mean, where z is any value greater than 1.  
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Define 'empirical rule'.   *only used when symmetrical, bell-curve distribution* 68% of data is within 1 standard deviation, 95% is within 2 sd, and almost all is within 3 sd.  
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Explain how to detect an outlier.   An outlier has a z-score of 3 or more (it is 3 or more standard deviations away from the mean).  
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Combinations   ---  
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Permeutations   ---  
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Draw a Tree Diagram.   ...  
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Combinations nCr    
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Define 'Intersection'.   The points belonging to A and B.  
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Define 'mutually exclusive'.   Neither A nor B have any similar points.  
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