lecture_notes_10_19_07 - Testing Genetic Hypotheses and...

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Testing Genetic Hypotheses and Measuring Linkage, outline - Lecture 5 2007 Probability and Testing Genetic Hypotheses [Reading: SS 51-57] Testing genetic ratios in Mendelian experiments Mendelian experiments generate results that rarely fit expectations exactly Geneticists evaluate results with probability, the frequency of the occurrence of an event The chi-square test Statistically evaluates the validity of genetic predictions (goodness of fit) by comparing observed data to expected values Chi-square = Sum of (Observed – Expected) 2 / Expected Answers the question: Is the hypothesis established in the Punnet Square correct? Selecting the appropriate chi-square critical value (numerical values which differentiate acceptance or rejection of a hypothesis) •Determine degrees of freedom –Number of genotypic/phenotypic categories in your experiment, minus 1 –So df = 1 for testing 3:1 ratio, df = 3 for 9:3:3:1 ratio •Select desired level of confidence –Margin of error you are willing to accept in drawing conclusions
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This note was uploaded on 04/29/2008 for the course BIOCORE 301 taught by Professor Howell during the Fall '07 term at Wisconsin.

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