TEST BANK FOR Practice of Statistics in the Life Sciences 4th Edition by Brigitte Baldi & David Moore All Chapters 1-28

TEST BANK FOR Practice of Statistics in the Life Sciences 4th Edition by Brigitte Baldi & David Moore All Chapters 1-28

INTRODUCTION
Chapter
1
• explain how experiments differ from observational
studies.
• discuss the concepts of placebo effect, blinding, and
confounding.
• discuss the role of random sampling in
statistics.
Objectives
In this chapter we will look at a series of examples of areas in the life sciences in
which statistics is used, with the goal of understanding the scope of the field of
statistics. We will also
1.1 Statistics and the Life Sciences
Researchers in the life sciences carry out investigations in various settings: in the
clinic, in the laboratory, in the greenhouse, in the field. Generally, the resulting data
exhibit some variability. For instance, patients given the same drug respond somewhat differently; cell cultures prepared identically develop somewhat differently;
adjacent plots of genetically identical wheat plants yield somewhat different
amounts of grain. Often the degree of variability is substantial even when experimental conditions are held as constant as possible.
The challenge to the life scientist is to discern the patterns that may be more or
less obscured by the variability of responses in living systems. The scientist must try
to distinguish the “signal” from the “noise.”
Statistics is the science of understanding data and of making decisions in the
face of variability and uncertainty. The discipline of statistics has evolved in
response to the needs of scientists and others whose data exhibit variability. The
concepts and methods of statistics enable the investigator to describe variability and
to plan research so as to take variability into account (i.e., to make the “signal”
strong in comparison to the background “noise” in data that are collected). Statistical methods are used to analyze data so as to extract the maximum information and
also to quantify the reliability of that information.
We begin with some examples that illustrate the degree of variability found in
biological data and the ways in which variability poses a challenge to the biological
researcher. We will briefly consider examples that illustrate some of the statistical
issues that arise in life sciences research and indicate where in this book the issues
are addressed.
The first two examples provide a contrast between an experiment that showed
no variability and another that showed considerable variability.
2 Chapter 1 Introduction
Vaccine for Anthrax Anthrax is a serious disease of sheep and cattle. In 1881, Louis
Pasteur conducted a famous experiment to demonstrate the effect of his vaccine
against anthrax. A group of 24 sheep were vaccinated; another group of 24 unvaccinated sheep served as controls. Then, all 48 animals were inoculated with a virulent
culture of anthrax bacillus. Table 1.1.1 shows the results.1 The data of Table 1.1.1
show no variability; all the vaccinated animals survived and all the unvaccinated
animals died.
Example
1.1.1
Bacteria and Cancer To study the effect of bacteria on tumor development, researchers used a strain of mice with a naturally high incidence of liver tumors. One
group of mice were maintained entirely germ free, while another group were exposed to the intestinal bacteria Escherichia coli. The incidence of liver tumors is
shown in Table 1.1.2.2
Example
1.1.2
In contrast to Table 1.1.1, the data of Table 1.1.2 show variability; mice given the
same treatment did not all respond the same way. Because of this variability, the
results in Table 1.1.2 are equivocal; the data suggest that exposure to E. coli increases the risk of liver tumors, but the possibility remains that the observed difference in
percentages (62% versus 39%) might reflect only chance variation rather than an
effect of E. coli. If the experiment were replicated with different animals, the
percentages might change substantially.
One way to explore what might happen if the experiment were replicated is to
simulate the experiment, which could be done as follows. Take 62 cards and write
“liver tumors” on 27 ( ) of them and “no liver tumors” on the other
35 ( ). Shuffle the cards and randomly deal 13 cards into one stack (to correspond to the E. coli mice) and 49 cards into a second stack. Next, count the number
of cards in the “E. coli stack” that have the words “liver tumors” on them—to correspond to mice exposed to E. coli who develop liver tumors—and record whether
this number is greater than or equal to 8. This process represents distributing
27 cases of liver tumors to two groups of mice (E. coli and germ free) randomly, with
E. coli mice no more likely, nor any less likely, than germ-free mice to end up with
liver tumors

Practice of Statistics in the Life Sciences Exam,Practice of Statistics in the Life Sciences Test,Practice of Statistics in the Life Sciences Flashcard,Practice of Statistics in the Life Sciences quiz,Practice of Statistics in the Life Sciences Practice,Practice of Statistics in the Life Sciences Practice test,Practice of Statistics in the Life Sciences Practice flashcard,Practice of Statistics in the Life Sciences Practice exam,Practice of Statistics in the Life Sciences Study guide,Practice of Statistics in the Life Sciences Practice questions,Practice of Statistics in the Life Sciences Questions,Practice of Statistics in the Life Sciences Practice questions and answers,Practice of Statistics in the Life Sciences Questions and answers,Practice of Statistics in the Life Sciences pdf,Practice of Statistics in the Life Sciences quizlet,Practice of Statistics in the Life Sciences reddit,Practice of Statistics in the Life Sciences Answer sheet,Practice of Statistics in the Life Sciences Answer key,Practice of Statistics in the Life Sciences Pdf free,Practice of Statistics in the Life Sciences Exam help,Practice of Statistics in the Life Sciences Cheat sheet,Practice of Statistics in the Life Sciences quiz bank,Practice of Statistics in the Life Sciences Questions bank,Practice of Statistics in the Life Sciences Practice Guide,Practice of Statistics in the Life Sciences Guide,Practice of Statistics in the Life Sciences Testbank,Practice of Statistics in the Life Sciences Practice Answers,Practice of Statistics in the Life Sciences Answers,Practice of Statistics in the Life Sciences Exam prep,Practice of Statistics in the Life Sciences Prep,Practice of Statistics in the Life Sciences Pdf download,Practice of Statistics in the Life Sciences Flashcards,Practice of Statistics in the Life Sciences Real questions,Practice of Statistics in the Life Sciences Actual questions,Practice of Statistics in the Life Sciences Real Questions and answers,Practice of Statistics in the Life Sciences Actual Questions and answers,Practice of Statistics in the Life Sciences Exam review,Practice of Statistics in the Life Sciences Review,Practice of Statistics in the Life Sciences Exam questions,Practice of Statistics in the Life Sciences Exam questions and answers,Practice of Statistics in the Life Sciences Practice test pdf,Practice of Statistics in the Life Sciences Practice test quizlet,Practice of Statistics in the Life Sciences Practice test Reddit,Practice of Statistics in the Life Sciences Practice test quizlet multiple choice,Practice of Statistics in the Life Sciences Exam study guide,Practice of Statistics in the Life Sciences Practice test free,Practice of Statistics in the Life Sciences Test questions,Practice of Statistics in the Life Sciences Exam study guide,Practice of Statistics in the Life Sciences Practice exam free,Practice of Statistics in the Life Sciences Practice tests free,Practice of Statistics in the Life Sciences Exam practice test,Practice of Statistics in the Life Sciences Exam test questions,Practice of Statistics in the Life Sciences Exam questions and answers,Practice of Statistics in the Life Sciences Exam practice test