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Practice Exam 4 - Introductory Biostatistics | BIOL 283, Exams of Biology

Material Type: Exam; Class: INTRODUCTORY BIOSTATS; Subject: Biology (Univ); University: Western Kentucky University; Term: Fall 2005;

Typology: Exams

Pre 2010

Uploaded on 07/29/2009

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Biology 283 Name __________________________
Fall Semester 2005
Exam #4 ID# __________________________
Definitions. Choose any 10 (4 points each).
Association vs. causality –
Positive correlation –
Covariance –
Y intercept –
Regression equation -
Best-fit line –
Residual –
Coefficient of determination –
Goodness-of-fit test –
Observed vs. expected distributions –
Row total vs. column total –
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Biology 283 Name __________________________ Fall Semester 2005 Exam #4 ID# __________________________

Definitions. Choose any 10 (4 points each).

Association vs. causality –

Positive correlation –

Covariance –

Y intercept –

Regression equation -

Best-fit line –

Residual –

Coefficient of determination –

Goodness-of-fit test –

Observed vs. expected distributions –

Row total vs. column total –

Short Answer. Answer both questions (5 points each).

  1. White-throated sparrows occur in two distinct color morphs – 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 r 2 : 0.

Estimate SE t p b 0 18.63 0.75 24.84 0. b 1 - 1.63 0.21 7.76 0.

  1. While we would like to believe that physicians’ prescription of medications is based solely on their evaluation of the scientific evidence of the relative benefits and potential detrimental consequences of alternative drugs, in fact there are multiple factors that come into play. Such possible factors include the influence of marketing and sales efforts by pharmaceutical companies, the cost of various prescription drugs, their time on the market, and the economic status and heath plan coverage of the patients. From an corporate standpoint, these factors all influence the supply and demand of a drug, and thus impact its market price. The data below outline the manufacturing cost and market price per day of use for 12 common medications.

Manufacturing cost/day ($) 0.02 0.06 0.18 0.35 0.40 0.48 0.63 0.80 1.06 1.10 1.66 2. Market price/day ($) 0.31 0.23 0.66 1.07 1.65 0.52 1.08 1.24 1.49 1.72 2.48 2.

In case you need them, the mean and standard deviations for manufacturing cost are 0.73 and 0.63, and the mean and standard deviation for market price are 1.25 and 0.77.

a. Based on these data, is there any evidence to suggest that there is a relationship between the manufacturing cost of these drugs and their market price? In your answer, state the appropriate null hypothesis, carry out the appropriate statistical test to support your interpretation. Show your work. ( points)

b. What led you to choose the statistical method you did, What qualitative conclusions or patterns can you draw from the data as a result? (10 points)