Basic Statistics

2 INITIAL STEPS

accompanying graphic programs have made it possible to obtain attractive and mean-
ingful displays of data without having to employ skilled graphic artists.
The second purpose is to draw conclusions that can be applied to other cases; this
is called statistical inference. For example, in studying the effects of a certain drug
on patients with asthma, one may want to do more than describe what happened to
the particular patients under study. One usually wishes to decide how to treat patients
with asthma in the future.
Biostatistical techniques are now widely used both in scientific articles and in
articles appearing in newspapers and on television. Learning to interpret statistical
summaries of data and statistical tests enables people to evaluate what they are reading
or hearing and to decide for themselves whether or not it is sensible.
Biostatistical concepts and techniques are useful for researchers who will be doing
research in medicine or public health. Here, the researchers need to know how to
decide what type of study to use for their research project, how to execute the study
on patients or well people, and how to evaluate the results. In small studies, they may
be totally responsible for the biostatistical analysis, and in large studies, they may
work with a professional biostatistician. In either case, knowing the basic concepts
and vocabulary of biostatistics will improve the research.

1.2 INITIAL STEPS IN DESIGNING A BIOMEDICAL STUDY

In this section we discuss setting study objectives and making a conceptual model of

the disease process. We also give two measures of evaluating how common a disease

condition is.

1.2.1 Setting Objectives

“If you do not know where you are going, any road will get you there” is a disparaging

remark that applies to planning a research project as well as to traveling. Thejirst

step in evaluating a study or in planning for one is to determine the major objective

of the study. Time spent in writing a clear statement of purpose of the study will save

time and energy later, especially in group projects.

In biomedical and public health studies two general types of objectives underlie

many of the studies that are performed. Broadly stated, these objectives are:

1. To determine the desirability of different treatments or preventive measures to
   reduce disease.


2. To assess the effects of causal or risk factors on the occurrence or progression
   of disease.

Here, the word disease has been used to stand for any unwanted medical or psy-

chological condition. A risk factor may often be a genetic predisposition, an envi-

ronmental exposure, or a patient’s lifestyle, over which the researcher has little or no

control.