Download Practice Exam 4 - Introductory Biostatistics | BIOL 283 and more Exams Biology in PDF only on Docsity! Biology 283 Name __________________________ Fall Semester 2005 Exam #4 ID# __________________________ Definitions. Choose any 10 (4 points each). Association vs. causality โ Positive correlation โ Covariance โ Y intercept โ Regression equation - Best-fit line โ Residual โ Coefficient of determination โ Goodness-of-fit test โ Observed vs. expected distributions โ Row total vs. column total โ Short Answer. Answer both questions (5 points each). 1. White-throated sparrows occur in two distinct color morphs โ brown and white. It was suspected that females prefer to mate with males whose coloration is different from their own. This phenomenon is known as negative assortative mating. Suppose you were interested in testing the validity of this hypothesis. You decide to study 100 nesting pairs of birds from a population outside Indianapolis, IN. For each pair you record the phenotype of the male and the phenotype of the female. How would you go about analyzing these data; that is, what is the appropriate statistical test to employ and why ? Refer to the nature of the data set and assumptions of the various tests to support your conclusion. 2. You are employed by the National Thoroughbred Racing Association (NTRA) to examine the relationship between sire's age and conception rate (number of successful pregnancies out of 25 fertilizations). The goal is to learn something about the performance of valuable sires over time. You study groups of sires at ages 3, 6, 9, 12, 15, 18 and 21. The results from the analysis are summarized below. What conclusions can you draw about the predictability, significance and strength of the relationship ? Refer to specific statistical descriptors to support your answer. Dep. Var.: Conception r : 0.76 r2: 0.58 Estimate SE t p b0 18.63 0.75 24.84 0.001 b1 - 1.63 0.21 7.76 0.030
