Creswell_Research_Design_ Qualitative Quantitative and Mixed Methods Approaches 2018 5th Ed

Participants
Readers need to know about the selection, assignment, and number of participants who will take part in the
experiment. Consider the following suggestions when writing the method section plan for an experiment:
Describe the procedures for recruiting participants to be in the study, and any selection processes used.
Often investigators aim to recruit a study sample that shares certain characteristics by formally stating
specific inclusion and exclusion study criteria when designing their study (e.g., inclusion criterion:
participants must be English language speaking; exclusion criterion: participants must not be children
under the age of 18). Recruitment approaches are wide-ranging, and can include random digit dialing of
households in a community, posting study recruitment flyers or e-mails to targeted communities, or
newspaper advertisements. Describe the recruitment approaches that will be used and the study
compensation provided for participating.
One of the principal features distinguishing an experiment from a survey study design is the use of
random assignment. Random assignment is a technique for placing participants into study conditions of
a manipulated variable of interest. When individuals are randomly assigned to groups, the procedure is
called a true experiment. If random assignment is used, discuss how and when the study will randomly
assign individuals to treatment groups, which in experimental studies are referred to as levels of an
independent variable. This means that of the pool of participants, Individual 1 goes to Group 1,
Individual 2 to Group 2, and so forth so that there is no systematic bias in assigning the individuals.
This procedure eliminates the possibility of systematic differences among characteristics of the
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