Evidence-Based Practice for Nurses

KEY TERMS

bivariate analysis:

The use of statistics

to describe the

relationship

between two

variables

multivariate

analysis: The use of

statistics to describe

the relationships

among three or

more variables

1. To describe the frequency of the single variable myocardial
   infarction in adults ages 30–49, which of the following could
   be used? (Select all that apply.)
   a. Descriptive statistics
   b. Inferential statistics
   c. Univariate analysis
   d. Bivariate analysis

TEST YOUR KNOWLEDGE 13-1

How did you do? 1. a, c

13.2 Using Frequencies

to Describe Samples

FYI

There are two types of statistics: descriptive

and inferential. Descriptive statistics describe,

summarize, and synthesize collected data,

while inferential statistics involve analysis of

data as the basis for predictions related to

the phenomenon of interest.

At the end of this section, you will be able to:

‹ Identify how frequencies can be graphically depicted

Information about the frequency, or how often, a variable
is found to occur may be presented as either ungrouped
or grouped data. Ungrouped data are primarily used to
present nominal and ordinal data where the raw data
represents some characteristic of the variable. In contrast,
with interval- and ratio-level data, the raw data are col-
lapsed (grouped) into smaller classifications to make the
data easier to interpret. Table 13-2 provides an example
of how categorical data about a sample may be presented in ungrouped format.

Ungrouped data are rarely presented when reporting on continuous variables
such as age, scores on scales, time, or physiological variables (e.g., temperature,
blood pressure, cell counts). For example, if readers of an article were presented
with a set of ages for 20 different participants in the study, it would be difficult
to make sense of this raw data (see Table 13-3). However, if the numbers were
arranged in a frequency distribution and graphed, they would make much more
sense to the readers. Before a graph can be constructed, the researcher must
create a frequency distribution table. First, the raw data are sorted, usually in
ascending order. Next, the number of times each value occurs is tallied, and
the frequency of each event is recorded in the table. Table 13-3 shows how the
raw data can be organized to more clearly present the information. The table

13.2 Using Frequencies to Describe Samples 333