Basic Research Design

Once the research question has been formulated, it is critical that you select the appropriate research methodology to answer the question.   The type of research question will typically dictate the methodology that will be employed.  The reliability and validity of the results depends on upon proper selection of the research approach and design.  Before deciding on a particular research design, it is important that you are familiar with research terminology that you will need to consider when choosing your methodology.  Two of the most important concepts are variables and sampling.  The following discussion of these topics will help you consider variables and sampling in relation to your SoTL project and will ultimately assist you in choosing a research design.

Types of Variables

It is very important when designing a research study that you fully understand the variables in the study in order for the results to be valid and have meaning.  A variable is something in the study that can be changed such as a characteristic or a value. The most common types of variables, especially when study cause and effect relationships, are the independent and dependent variables.  The independent variable is the one that can be controlled or manipulated.  The dependent variable is the one that is measured by the experimenter.  For example, if a researcher wanted to study the effects of fertilizer on plant growth, the independent variable would be the amount of fertilizer and the dependent variable would be the height of the plant.  It is very important that the research can identify these variables in a study and describe how these variables are measured and defined.  For practice in identifying these variables, this YouTube video below defines dependent and independent variables and provides numerous examples and opportunities to practice identifying each variable in sample research problems:  Variables

The following YouTube video provides additional and more detailed information regarding other types of variables used in research studies. This 20 minute video contains a Research Methods lecture that uses examples in psychology to discuss types of variables.

Sampling

Researchers often cannot study every member of a population or group.  Rather, they collect data from a subset of that population or group which is called a sample.  The data collected and observations made are used to make inferences about the entire population or group with the idea that the sample will be representative of the larger population. There are two main approaches to sampling – probability sampling and nonprobability sampling.  Probability sampling is when all members of a population or elements of a group have the same opportunity and chance of being included in the study.  Following are the three most common types of probability sampling:

• Simple random sample – all members of a population or elements have an equal chance of being selected and sampling is done is a single staged time frame where each member is selected individually.
• Systematic samples – taken by starting with a randomly selected member of population or element and then selecting every nth member of the population. For example – selecting ever 50^th name on a list of community members.
• Cluster samples – Starts with first selecting groups of elements or members of populations in clusters (schools, people living on particular block, etc..) and then selecting individuals from each cluster.

Nonprobability sampling occurs when members of the study or elements of a group are selected based on availability (perhaps they volunteered) or on the researcher’s judgment that they will be representative.  This is often called convenience sampling because researchers use whatever individuals are available.

In order for the results to be valid, other factors that must be considered in sampling are the response rate, sampling size and sampling error.   Often times in SoTL research, a entire classroom of students is sampled and choosing a sampling technique may not be a factor in research design.  However, sampling considerations may be a factor in some SoTL projects and therefore, it is important to be familiar with the basic terminology.  For more information about variables and sampling, see the resources available on GCU Research Tutorial - Sampling & Variables.

Quantitative and Qualitative Designs

There are two main approaches to a research problem - quantitative and qualitative methods.  Quantitative methods are used to examine the relationship between variables with the primary goal being to analyze and represent that relationship mathematically through statistical analysis.  This is the type of research approach most commonly used in scientific research problems.  Qualitative methods are chosen when the goal of the research problem is to examine, understand and describe a phenomenon.  These methods are a common choice in social science research problems and are often used to study ideas, beliefs, human behaviors and other research questions that do not involve studying the relationship between variables. Once the main approach to the research problem has been determined,  there are several research designs for each type of approach that may be considered.  

The following videos from the GCU CIRT department provide additional information about quantitative and qualitative research designs commonly used in SoTL projects.

Choosing a Design

The following table lists and describes the most common research designs used at Grand Canyon University.  Different research books will use different terms for similar types of research.  However, the research designs identified in this document are fairly common in terms of their use and their terminology.

Types of Research Designs