Final_sol - is 100 . 8 = 80. Similarly, there are 900 true...

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ECEN 689 - Statistical Computation in Genomic Signal Processing Final Exam Solutions – Fall 2009 Problem 1. (30 points) Let the compound be C x O y H w , where x, y, w need to be determined. From the binomial and convolution properties, we have the situation in the following figure: Therefore, we need to solve the following system of equations: 1 . 08 x = 10 . 8 100 1 2 x ( x - 1) 0 . 0108 2 + 0 . 205 y = 1 . 34 The solution of which is easily determined to be x = 10 and y = 4. To determine w , first note that the spacing between peaks is 0.5, and hence the charge state is z = 2. Therefore the mass for the base peak is 2 × 102 = 204. Hence, we have 10 × 12 + 4 × 16 + w = 204 w = 20 and the formula of the compound is C 10 O 4 H 20 . Problem 2. (20 points) (a) The sensitivity is the true positive rate = 72 / 100 = 72%, while the specificity is 1 - false positive rate = 1 - 72 / 900 = 92%. (b) There are 100 true positives, so the expected number of true positives obtained by the test
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Unformatted text preview: is 100 . 8 = 80. Similarly, there are 900 true negatives, so the expected number of false positives obtained by the test is 900 (1-. 95) = 45. The expected lenght of the list is therefore 80 + 45 = 125. Problem 3. (20 points) (a) Array 24 contains a percentage of present calls around 30%, clearly smaller than the value 40% typically observed in Aymetrix human arrays. This may indicate that array 24 is unreliable. 1 (b) Normalization needs to be applied to bring the average M values close to zero over all values of A. Normalization must be nonlinear (e.g. Lowess), as linear normalization would not work uniformly well over all values of A. Problem 4. (30 points) Write TRUE or FALSE for each of the following statements. (a) FALSE. (b) TRUE. (c) FALSE. (d) FALSE. (e) TRUE. (f) TRUE. 2...
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Final_sol - is 100 . 8 = 80. Similarly, there are 900 true...

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