# Lec3 - A biostatistics professor gave his class two tests...

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Unformatted text preview: A biostatistics professor gave his class two tests. 84% of the class passed both tests and 92% of the class passed the first test. What percent of those who passed the first test also passed the second test? You have been training to enter a spelling bee and can now correctly spell words 94% of the time. What is the probability that you spell the first two words correctly and then miss the third? Suppose that every driver has probability of 0.02 of being intoxicated. Intoxicated drivers have a probability of 0.00045 of getting into an accident while for unintoxicated drivers that probability is 0.00016. What is the probability of both being intoxicated and not having an accident? A biostatistics professor gave his class two tests. 84% of the class passed both tests and 92% of the class passed the first test. What percent of those who passed the first test also passed the second test? Pr{Pass 2nd|Pass 1st} = P{Pass both}/P{Pass 1st} = 0.84/0.92=0.91 You have been training to enter a spelling bee and can now correctly spell words 94% of the time. What is the probability that you spell the first two words correctly and then miss the third? Pr{spell 1st AND spell 2nd AND miss 3rd} = Pr{spell 1st} x Pr{spell 2nd} x Pr{miss 3rd} = 0.94 x 0.94 x (1 - 0.94) = 0.053 correct wrong 0.94 0.06 correct wrong 0.94 0.06 correct wrong 0.94 0.06 correct wrong 0.94 0.06 … A biostatistics professor gave his class two tests. 84% of the class passed both tests and 92% of the class passed the first test. What percent of those who passed the first test also passed the second test? Pr{Pass 2nd|Pass 1st} = P{Pass both}/P{Pass 1st} = 0.84/0.92=0.91 You have been training to enter a spelling bee and can now correctly spell words 94% of the time. What is the probability that you spell the first two words correctly and then miss the third? Pr{spell 1st AND spell 2nd AND miss 3rd} = Pr{spell 1st} x Pr{spell 2nd} x Pr{miss 3rd} = 0.94 x 0.94 x (1 - 0.94) = 0.053 Suppose that every driver has probability of 0.02 of being intoxicated. Intoxicated drivers have a probability of 0.00045 of getting into an accident while for unintoxicated drivers that probability is 0.00016. What is the probability of both being intoxicated and not having an accident? Pr{intoxicated AND no accident} = Pr{intoxicate} x Pr{no accident|intoxicated} = 0.02 x (1 - 0.00045) = 0.02 FLASHBACK I … Relative frequency Relative frequency = Frequency/Total Relative frequency 1/36 = 0.03 4/36 = 0.11 7/36 = 0.19 8/36 = 0.22 8/38 = 0.22 3/36 = 0.08 2/36 = 0.06 1/36 = 0.03 0/36 = 0 2/36 = 0.06 1 1 2 3 4 5 6 7 8 9 2 4 6 8 1 1 2 1 4 1 6 1 8 2 Serum CK (u/Li) Frequency 0.05 0.1 0.15 0.2 0.25 Relative Frequency Relative frequency histogram Relative frequency distributions approximates the distribution of the data in the true population Smoothing the curve (continuous data) An idealization of the relative frequency distribution with very narrow classes Class width = 10 Class width = 5 Smooth Density curve: A smooth curve representing a frequency distribution...
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## This note was uploaded on 11/04/2009 for the course BIO 50935 taught by Professor Bryant during the Fall '09 term at University of Texas.

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Lec3 - A biostatistics professor gave his class two tests...

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