Evidence-Based Practice for Nurses

10.3 Validity and Reliability

1. Which of the following are advantages that questionnaires have over interviews? (Select
   all that apply.)
   a. Take less time to administer
   b. Provide for anonymity
   c. Allow for more in-depth responses
   d. Minimize socially desirable responses


2. Which of the following are physiological measures? (Select all that apply.)
   a. Blood pressure
   b. Grades on an exam
   c. Digoxin levels
   d. Mini-Mental State Examination


3. Match the terms:
   a. Nominal 1. Input and output measurement
   b. Ordinal 2. Temperature in degrees Celsius
   c. Interval 3. Type of cancer
   d. Ratio 4. Strength of contractions (mild, moderate, strong)

TEST YOUR KNOWLEDGE 10-2

How did you do? 1. a, b, d; 2. a, c; 3. a-3, b-4, c-2, d-1

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

‹ Identify types of random and systematic measurement errors

‹ Define validity and reliability

‹ Name strategies that researchers use to establish reliability and validity of various

measures

‹ Recognize questions used to appraise quantitative data collection methods

Measurement Error

Although it may seem that creating surveys and instruments is easy, research-
ers actually spend a significant amount of time designing them. They do this
to reduce measurement error so that they know the measurements provide a
true reflection of the sample characteristics. In any measurement, the goal is
for the observed measurement to be as close to the true measurement as pos-
sible. The equation O = T + E illustrates this concept. O stands for the observed
score. This is the actual number or value that is obtained from the instrument
regarding the characteristic. T stands for the true score, the actual amount of the

KEY TERM

measurement

error: The difference

between the true

score and the

observed score

10.3 Validity and Reliability 263