CHAPTER 1 Biostatistics 101 9

Concentrating on Epidemiologic Research

This book covers topics that are applicable to all areas of biostatistics, concentrat-

ing on methods that are especially relevant to epidemiologic research — studies

involving people. This includes clinical trials, which are experiments done to

develop therapeutic interventions such as drugs. Because policy in healthcare is

often based on the results from clinical trials, if you make mistake analyzing

clinical trial data, it can have disastrous and wide-ranging human and financial

consequences. Even if you don’t expect to ever work in a domain that relies heav-

ily on clinical trials (such as drug development research), ensuring that you have

a working knowledge of how to manage the statistical issues seen in clinical trials

is critical.

Three chapters discuss clinical trials:»

» ^{Chapter 5 describes the statistical aspects of clinical trials as three phases.}

First, it covers the design phase, where a study protocol is written. Next, it

describes the execution phase, where data are collected, and efforts are made

to prevent invalid or missing data. In the final phase, data from the study are

analyzed and interpreted to answer the hypotheses.»

» ^{Chapter 7 presents epidemiologic study designs and explains the importance}

of the clinical trial as a study design.»

» ^{Chapter 20 explains the role well-designed clinical trials play in accruing}

evidence of causal inference in biostatistics.

Much of the work in biostatistics is using data from samples to make inferences

about the background population from which the sample was drawn. Now that we

have large databases, it is possible to easily take samples of data. Chapter  6

provides guidance on different ways to take samples of larger populations so you

can make valid population-based estimates from these samples. Sampling is

especially important when doing observational studies. While clinical trials

covered are experiments, where participants are assigned interventions, in obser-

vational studies, participants are merely observed, with data collected and statis-

tics performed to make inferences. Chapter 7 describes these observational study

designs, and the statistical issues that need to be considered when analyzing data

arising from such studies.

Data used in biostatistics are often collected in online databases, but some data

are still collected on paper. Regardless of the source of the data, they must be put

into electronic format and arranged in a certain way to be able to be analyzed

using statistical software. Chapter 8 is devoted to describing how to get your data

into the computer and arrange it properly so it can be analyzed correctly. It also