A-2 APPENDIX A
In this appendix we will take a look at describing data—seeing if groups differ from
each other and seeing if two variables are related to each other. Those are the basic ideas
of psychological statistics. The more advanced techniques are just bigger and better ver-
sions of these ideas. Many psychology students sometimes panic at the thought of taking
statistics. However, it is crucial to the field and not really that hard if you put your mind
to it and don’t freeze yourself up. Why is it so important? Even if you are not the kind of
psychologist who uses statistics on a daily basis, all psychologists have to be able to read
and understand the research others are doing, and understanding what the statistical
analyses of that research is really saying is crucial. Here’s a practical hint: Students with
good research and statistical skills are much more employable and make more money
than those who don’t try to master research skills. It’s nice to care about people, but you
need all the skills you can get in today’s world. Statistics and research design is one really
profitable set of skills.Practice Quiz How much do you remember?
Pick the best answer.- ____ is the branch of mathematics that is concerned with the
collection and interpretation of data from samples.
a. Statistics
b. Psychometrics
c. Probabilities
d. Coefficients - What is the primary advantage of using statistical analysis in a
research study?
a. It allows you to confirm the hypotheses that were set forth when
you started the research.
b. It allows you to attempt to account for any of the error that exists
in virtually any body of data.
c. It allows you to demonstrate that you, as the researcher, are
competent to examine and interpret the results of your research.
d. It allows you to get your research proposal approved by an
Institutional Review Board and, later, allows your research to be
published.- Which of the following is the underlying question of any
psychological research statistics?
a. Is behavior determined by “nature” or “nurture”?
b. Do people want to be “good” or “bad” in their general behaviors?
c. Is there a singular commonality that underlies all behaviors?
d. Are groups different from each other, and are two variables
related to each other?
Descriptive Statistics
Descriptive statistics are a way of organizing numbers and summarizing them so that
they can be understood. There are two main types of descriptive statistics:- Measures of Central Tendency. Measures of central tendency are used to sum-
marize the data and give you one score that seems typical of your sample. - Measures of Variability. Measures of variability are used to indicate how spread
out the data are. Are they tightly packed or are they widely dispersed?
The actual descriptive statistics are best understood after we explain the concept of
a frequency distribution.
One way psychologists get started in a research project is to look at their data, but
just looking at a list of numbers wouldn’t do much good. So we make a graph or chart.
Then we can look for patterns.
FREQUENCY DISTRIBUTIONS
A.2 Describe the types of tables and graphs that represent patterns in data.
A frequency distribution is a table or graph that shows how often different numbers, or
scores, appear in a particular set of scores. For example, let’s say that you have a sam-
ple of 30 people, the size of some psychology classes. You ask them how many glasses
of water they drink each day. You could represent the answers as shown in Ta b l e A. 1.descriptive statistics
a way of organizing numbers and
summarizing them so that patterns
can be determined.frequency distribution
a table or graph that shows how often
different numbers or scores appear in
a particular set of scores.Z01_CICC7961_05_SE_APPA.indd 2 9/2/16 11:57 PM