What kind of research method is used when a researcher controls the independent variable in a study?

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

By Dr. Saul McLeod, published 2012

The experimental method involves the manipulation of variables to establish cause and effect relationships. The key features are controlled methods and the random allocation of participants into controlled and experimental groups.

An experiment is an investigation in which a hypothesis is scientifically tested. In an experiment, an independent variable (the cause) is manipulated and the dependent variable (the effect) is measured; any extraneous variables are controlled.

An advantage is that experiments should be objective. The views and opinions of the researcher should not affect the results of a study. This is good as it makes the data more valid, and less biased.

There are three types of experiments you need to know:

1. Lab Experiment

A laboratory experiment is an experiment conducted under highly controlled conditions (not necessarily a laboratory), where accurate measurements are possible.

The researcher decides where the experiment will take place, at what time, with which participants, in what circumstances and using a standardized procedure.

Participants are randomly allocated to each independent variable group. An example is Milgram’s experiment on obedience or Loftus and Palmer's car crash study.

• Strength: It is easier to replicate (i.e. copy) a laboratory experiment. This is because a standardized procedure is used.
• Strength: They allow for precise control of extraneous and independent variables. This allows a cause and effect relationship to be established.
• Limitation: The artificiality of the setting may produce unnatural behavior that does not reflect real life, i.e. low ecological validity. This means it would not be possible to generalize the findings to a real life setting.
• Limitation: Demand characteristics or experimenter effects may bias the results and become confounding variables.

2. Field Experiment

Field experiments are done in the everyday (i.e. real life) environment of the participants. The experimenter still manipulates the independent variable, but in a real-life setting (so cannot really control extraneous variables).

An example is Holfing’s hospital study on obedience.

• Strength: behavior in a field experiment is more likely to reflect real life because of its natural setting, i.e. higher ecological validity than a lab experiment.
• Strength: There is less likelihood of demand characteristics affecting the results, as participants may not know they are being studied. This occurs when the study is covert.
• Limitation: There is less control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.

3. Natural Experiment

Natural experiments are conducted in the everyday (i.e. real life) environment of the participants, but here the experimenter has no control over the independent variable as it occurs naturally in real life.

For example, Hodges and Tizard's attachment research (1989) compared the long term development of children who have been adopted, fostered or returned to their mothers with a control group of children who had spent all their lives in their biological families.

• Strength: behavior in a natural experiment is more likely to reflect real life because of its natural setting, i.e. very high ecological validity.
• Strength: There is less likelihood of demand characteristics affecting the results, as participants may not know they are being studied.
• Strength: Can be used in situations in which it would be ethically unacceptable to manipulate the independent variable, e.g. researching stress.
• Limitation: They may be more expensive and time consuming than lab experiments.
• Limitation: There is no control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.

Ecological validity

The degree to which an investigation represents real-life experiences.

Experimenter effects

These are the ways that the experimenter can accidentally influence the participant through their appearance or behavior.

Demand characteristics

The clues in an experiment that lead the participants to think they know what the researcher is looking for (e.g. experimenter’s body language).

Independent variable (IV)

Variable the experimenter manipulates (i.e. changes) – assumed to have a direct effect on the dependent variable.

Dependent variable (DV)

Variable the experimenter measures. This is the outcome (i.e. result) of a study.

Extraneous variables (EV)

All variables, which are not the independent variable, but could affect the results (DV) of the experiment. EVs should be controlled where possible.

Confounding variables

Variable(s) that have affected the results (DV), apart from the IV. A confounding variable could be an extraneous variable that has not been controlled.

Random Allocation

Randomly allocating participants to independent variable conditions means that all participants should have an equal chance of taking part in each condition.

The principle of random allocation is to avoid bias in the way the experiment is carried out and to limit the effects of participant variables.

Order effects

Changes in participants’ performance due to their repeating the same or similar test more than once. Examples of order effects include:

(i) practice effect: an improvement in performance on a task due to repetition, for example, because of familiarity with the task;

(ii) fatigue effect: a decrease in performance of a task due to repetition, for example, because of boredom or tiredness.

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How to reference this article:

McLeod, S. A. (2012, January 14). Experimental method. Simply Psychology. www.simplypsychology.org/experimental-method.html

How to reference this article:

McLeod, S. A. (2012, January 14). Experimental method. Simply Psychology. www.simplypsychology.org/experimental-method.html

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