Evidence-Based Practice for Nurses

Interaction of Treatment and History

Interactions of treatment and history can also occur. This threat is concerned
with how the effects from the intervention might be changed by events occur-
ring in the past or in the future. For example, if the researcher found that the
computer-based intervention increased condom use, would those results be
generalizable to the future if a cure for HIV were to be discovered?

KEY TERM

interaction of

treatment and

history: A threat

to external validity

when historical

events affect the

intervention

1. What is the degree to which the results of studies can be generalized to other individuals,
   settings, or time called?
   a. External validity
   b. Construct validity
   c. Internal validity
   d. Statistical conclusion validity


2. During a study examining nurses’ job satisfaction, the union decides to hold a strike. This
   is which type of threat to internal validity?
   a. Selection bias
   b. Mortality
   c. History
   d. Testing


3. A researcher plans to observe children in a kindergarten class. Students have always been
   told to be on their best behavior when guests are present in the classroom. What is the
   greatest threat to external validity?
   a. Construct validity
   b. Hawthorne effect
   c. Selection
   d. Interaction of treatment setting

TEST YOUR KNOWLEDGE 6-2

How did you do? 1. a; 2. c; 3. b

6.3 Categorizing Designs According

to Time

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

‹ Differentiate the time dimension of data collection across retrospective, cross-

sectional, and longitudinal and prospective designs

6.3 Categorizing Designs According to Time 161