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

‹ Explain the three essential components of experimental designs

‹ Identify major experimental designs

‹ Discuss the advantages and disadvantages of various experimental designs

Quantitative Designs: Using

Numbers to Provide Evidence

Rosalind M. Peters

7.1 Experimental Designs

Quantitative designs can provide evidence that describes a phenomenon, explain relationships and differences
among variables, predict relationships and differences among variables, or determine causality (Campbell &
Stanley, 1966; Cook & Campbell, 1979). Experimental designs provide the best evidence for claiming
that a cause-and-effect relationship exists. This type of design often includes the terms pretest and posttest.
These terms refer to the point in time when data collection is taking place. Sometimes these are labeled
“before” and “after” designs because pretest means data are collected prior to or before the intervention
group receives the treatment, and posttest refers to data collected after the intervention is completed.
Experimental designs look for differences between treated and untreated subjects. Therefore, there must

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CHAPTER 7