Evidence-Based Practice for Nurses

is the term used when there are only two possible fixed responses, such as true

or false and yes or no.

Ordinal measurement represents the second lowest level of measurement. A

continuum of numeric values is used with small numbers representing lower

levels on the continuum and larger numbers representing higher values. How-

ever, although the values are ordered or ranked, the intervals are not meant to

be equal. For example, in a marathon the distance and time among those who

finish in first, second, and third are not equal; however, there is value to the

number assigned. Many questionnaires and scales use ordinal measurements.

Figure 10-5 provides examples of ordinal measures.

Interval measurement is a third level of measurement and uses a continuum

of numeric values, also known as continuous data. At this level, the values

have meaning and the intervals are equal. On interval scales, the zero point is

arbitrary and not absolute. The zero is not an indication of the true absence

of something. The best example of this is the Celsius scale. When measuring

temperature in Celsius, 0 does not mean the absence of temperature. In fact, it

is quite cold. Other examples of interval scores include intelligence measures,

personality measures, and manual muscle testing.

Continuous data are also collected using ratio measurement, which is the

highest level of measurement and uses a continuum of numeric values with

equal intervals and a zero point that is absolute. Age, weight, height, and

income are good examples of this type of measurement. VAS also provides

ratio measurement along with many other biochemical and physiological

measures.

Extremely

dissatisfied

1

Very

dissatisfied

2

Somewhat

satisfied

3

Very

satisfied

4

Extremely

satisfied

5

To what extent are you satisfied with the quality of care you received?

Put the following in order of importance to you. Assign 1 to the most important and 5 to the

least important.

______ Time with family

______ Satisfaction with work

______ Income

______ Health

______ Personal appearance

FIGURE 10-5 Examples of Ordinal Level Measurement

KEY TERM

continuous

data: Interval- or

ratio-level data that

use a continuum of

numeric values with

equal intervals

262 CHAPTER 10 Collecting Evidence