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Factorial Design
A factorial design contains two or more independent variables and one dependent variable. The independent variables, often called factors, must be categorical. Groups for these variables are often called levels. The dependent variable must be continuous, measured on either an interval or a ratio scale.
Suppose a researcher is interested in determining if two categorical variables [treatment condition and gender] affect a continuous variable [achievement]. The researcher decides to use a factorial design because he or she wants to examine population group means. A factorial analysis of variance will allow him or her to answer three questions. One question concerns the main effect of treatment: Do average achievement scores differ significantly across treatment conditions? Another question concerns the main effect of gender: Does the average achievement ...
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Main Effects
Main effects can be defined as the average differences between one independent variable [or factor] and the other levels of one or more independent variables. In other words, investigators identify main effects, or how one independent variable influences the dependent variable, by ignoring or constraining the other independent variables in a model. For instance, let us say there is a difference between two levels of independent variable A and differences between three levels of independent variable B. Consequently, researchers can study the presence of both factors separately, as in single-factor experiments. Thus, main effects can be determined in either single-factor experiments or factorial design experiments. In addition, main effects can be interpreted meaningfully only if the interaction effect is absent. This entry focuses on main ...
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What are the main types of qualitative approaches to research?
While there are many different investigations that can be done, a study with a qualitative approach generally can be described with the characteristics of one of the following three types:
Historical research describes past events, problems, issues and facts. Data are gathered from written or oral descriptions of past events, artifacts, etc. It describes “what was” in an attempt to recreate the past. It is different from a report in that it involves interpretation of events and its influence on the present. It answers the question: “What was the situation?”
Examples of Historical Research:
- A study of the factors leading to the historical development and growth of cooperative learning
- A study of the effects of the historical decisions of the United States Supreme Court on American prisons
- A study of the evolution of print journalism in the United States through a study of collections of newspapers
- A study of the historical trends in public laws by looking recorded at a local courthouse
Ethnographic research develops in-depth analytical descriptions of current systems, processes, and phenomena and/or understandings of the shared beliefs and practices of a particular group or culture. This type of design collects extensive narrative data [non-numerical data] based on many variables over an extended period of time in a natural setting within a specific context. The background, development, current conditions, and environmental interaction of one or more individuals, groups, communities, businesses or institutions is observed, recorded, and analyzed for patterns in relation to internal and external influences. It is a complete description of present phenomena.
One specific form of ethnographic research is called a case study. It is a detailed examination of a single group, individual, situation, or site.
A meta-analysis is another specific form. It is a statistical method which accumulates experimental and correlational results across independent studies. It is an analysis of analyses.
Examples of Ethnographic Research:
- A case study of parental involvement at a specific magnet school
- A multi-case study of children of drug addicts who excel despite early childhoods in poor environments
- The study of the nature of problems teachers encounter when they begin to use a constructivist approach to instruction after having taught using a very traditional approach for ten years
- A psychological case study with extensive notes based on observations of and interviews with immigrant workers
- A study of primate behavior in the wild measuring the amount of time an animal engaged in a specific behavior
Narrative research focuses on studying a single person and gathering data through the collection of stories that are used to construct a narrative about the individual’s experience and the meanings he/she attributes to them.
Examples of Narrative Research:
- A study of the experiences of an autistic student who has moved from a self-contained program to an inclusion setting
- A study of the experiences of a high school track star who has been moved on to a championship-winning university track team