To reach a port, we must sail—Sail, not tie at anchor—Sail, not drift.
The information provided in this chapter will assist the reader to:
Establish proper inclusion and exclusion criteria for research subjects.
Consider subject recruitment and select the most appropriate sampling technique.
Choose a suitable method for data collection from those reviewed (observation, interviews, surveys, record review, equipment use, assessments, or tests).
Understand the complexities of survey construction and where to locate additional resources to assist in this endeavor.
Examine the validity and reliability of proposed testing instruments before electing their use.
Comprehend differences between descriptive and inferential statistics used in data analysis.
Identify appropriate resources for statistical analysis.
Report results and synthesize them with existing literature to effectively draw conclusions.
CONSIDERATIONS IN QUANTITATIVE RESEARCH
To enable others to understand and apply your quantitative research, you will need to consider and identify the following: subject inclusion and exclusion criteria, recruitment and sampling methods, data collection techniques, and data analysis. Each of these topics will be covered in greater depth here.
Subject Inclusion and Exclusion Criteria
Subject inclusion and exclusion criteria are specific conditions set forth by the researchers that must be met for eligibility to participate in their study. The population of interest refers to the entire group of individuals, events, documents, or records that meet these criteria. Although the subjects in healthcare research are frequently individuals, they can also include records or events. (See Boxes 6-1 and 6-2 for examples.) In either case, those deemed eligible for participation in a study must meet a specific set of characteristics that have been established by the researcher before initiation of the study.
Subject inclusion criteria consist of characteristics or traits that subjects must have to qualify for participation in the study. For example, you might be interested in studying adults diagnosed with multiple sclerosis in the United States who are 40 to 60 years old and who are employed full time. If so, demographic data is collected before the study begins to ensure all participants meet these criteria. Subject exclusion criteria take into account undesirable features for participants. These could include subjects residing more than 50 miles from the research center, those who only work one or more part-time jobs, or those with impaired cognitive abilities that might influence performance on study measures, for instance.
Inclusion and exclusion criteria are determined based upon the literature review and goals for the study, and they typically evolve as the assumptions and theoretical base of the study unfold. Therefore, these criteria are established well in advance of the study’s beginning. It is important to identify all applicable criteria, so that readers have a clear understanding of the population being investigated.