Eunsook T. Koh

Experimental and Quasi-Experimental Research

Research design is the plan, structure, and strategy of investigation conceived so as to obtain answers to research quest ions and to control variance. Research design has two basic purposes: (1) to provide answers to research questions and (2) to control variability. The main technical function of research design is to control variance: Maximize systematic variability, control extraneous systematic variability, and minimize error variability.

Introduction to nutrition and health research

Preface. Acknowledgements. Part I: Overview of the Research Process. 1. Introduction to Research in Nutrition and Health. 2. Research Problem and Literature Review. 3. Framing a Research Problem: Hypotheses, Purposes, Objectives, and Questions. 4. Writing Method Sections. 5. Ethical Issues in Research and Scholarship. Part II: Statistical and Measurement Concepts in Research. 6. Statistical Concepts. 7. Relationships Among Variables. 8. Differences Among Groups. 9. Nonparametric Statistics. 10. Measuring Research Variables. Part III: Various Types of Research. 11. Experimental and Quasi-Experimental Research. 12. Descriptive Research and Qualitative Research. Part IV: Writing the Research Proposal and Results. 13. Results, Discussion, and Abstract. 14. Publications. 15. Writing the Research Proposal. Part V: Using Computers in Research. 16. Using Computers. Appendix: A. Statistical Tables. Subject Index.

Measuring Research Variables

“In its broadest sense, measurement is the assignment of numerals to objects or events according to rules (Stevens).” This definition of measurement accurately expresses the basic nature of measurement. A numeral is a symbol of the form: 1,2.3, ..., or I, II, III .... etc. There are four general levels of measurement: nominal, ordinal, interval, and ratio that we have already discussed in Chapter 6.

Differences Among Groups

Statistical techniques are used for describing and finding relationships among variables, as we discussed in Chapters 6 and 7. They are also used to detect differences among groups. The latter are most frequently used for data analysis in experimental and quasi-experimental research. They enable us to evaluate the effects of an independent [cause or treatment or categorical variables (gender, age, race, etc.)] variable on a dependent variable (effect, outcome).

Relationships Among Variables

In the previous chapter hypothesis testing was explained. Another area of inferential statistics involves determining whether a relationship between two or more variables exists. For example, nutritionists may want to know whether caffeine intake is related to heart disease, or whether person’s age is related to her blood pressure. A zoologist may want to know whether the birth weight of a certain animal is related to the life span of the animal. These are only a few of the many questions that can be answered by using the technique of correlation and regression analysis. Correlation is a statistical method used to determine whether a relationship between variables exists. Regression is a statistical method used to describe the nature of the relationship between variables — i.e., a positive or negative, linear or nonlinear relationship.

Descriptive Research and Qualitative Research

Descriptive research is a study of status and is widely used in education, nutrition, epidemiology, and the behavioral sciences. Its value is based on the premise that problems can be solved and practices improved through observation, analysis, and description. The most common descriptive research method is the survey, which includes questionnaires, personal interviews, phone surveys, and normative surveys. Developmental research is also descriptive. Through cross-sectional and longitudinal studies, researchers investigate the interaction of diet (e.g., fat and its sources, fiber and its sources, etc.) and life styles (e.g., smoking, alcohol drinking, etc.) and of disease (e.g., cancer, coronary heart disease) development. Observational research and correlational studies constitute other forms of descriptive research. Correlational studies determine and analyze relationships between variables as well as generate predictions. Descriptive research generates data, both qualitative and quantitative, that define the state of nature at a point in time. This chapter discusses some characteristics and basic procedures of the various types of descriptive research.

Results, Discussion, and Abstract

The results section is the most important part of the research report. The reports generated through research are perhaps the most common medium for researcher to communicate with both academic audience and the practical reader in the world of men. In another word, this section presents your contribution to knowledge, that is, what you found. Journal articles, master’s theses, and doctoral dissertations all have the same objectives.

Writing Method Sections

The question to be answered or the hypothesis to be tested now has to be turned into a practical project, which will consist of making observations on some form of biomedical material, performing clinical trials on patients, or carrying out experiments on animals or in vitro. The planning stage for the research should be described in the method section.

Framing a Research Problem: Hypotheses, Purposes, Objectives, and Questions

The problem chapter provides an overview of the study: statement of the purpose or problem to be addressed, title, introduction, hypothesis, delimitations (scope), limitations (variables that could not be controlled), and significance of the study.

Introduction to Research in Nutrition and Health

Research is simply a way of solving problems, and it is defined as planned studious and critical inquiry and examination aimed at the discovery and interpretation of new knowledge or expansion on a topic or idea. Quality assurance, surveys, new product evaluation, and case report are all examples of research. The purpose of these activities is to document “what works and what does not work,” which answers particular research questions. Useful research studies may be done to substantiate other previous investigations. Studies of diet and disease relationship and studies of various nutrition therapies are absolutely indispensable in substantiating the value of nutrition in the health care environment.