In the Quantitative Methodology, there are experimental (deals with the impact of an outcome, while having a controlling variable to see if the tested variable does have an impact), quasi-experimental (deals with a non-random sample but still measures the impact of an outcome) and non-experimental (deals with generalizing/inferring about a population) project designs.
For a non-experimental project design, surveys are used as an instrument to gather data and help produce quantitative/numeric data to help identify trends and sentiment from a sample of a total population (Creswell, 2013). The Pew Research Center (2015), wanted to analyze the changing attitudes on Gay Marriage a few days after the Supreme Court struck down the bans as unconstitutional, have asked:
Do you oppose/favor allowing gays and lesbians to marry legally? What is your current age? What is your Religious Affiliation? What is your Political Party? What is your Political Ideology? What is your Race? What is your gender?
Pew found that overall, since they were conducting this survey since 2001, they have seen that in every descriptive variable classifying people has shown an increase in acceptance for marriage, with an overall 55% approval rating to 39%. This example is not trying to explain a relationship but rather a trend.
For an experimental project design, it usually follows the following steps: Identification of participants, gathering of materials, draft and finalize procedures and setting up measures so that you can conduct the experiment and derive some results from it (Creswell, 2013).
When a participant in a study is randomly assigned to a control group or in other groups in an experiment it is considered a true experiment, if the participants in a study are not randomly assigned then it is considered a quasi-experiment (Creswell, 2013). In the famous Milgram Obedience Experiment (1974), an ad was posted to collect participants for a study on memory, but in fact, they were there to see if the presence of authority would compromise their internal morals to cause pain and sometimes delivering fatal shocks to another participant (an actor). About 2/3 of people were willing to administer the deadly shock because they had the presence of authority (a man in a white coat) telling them to continue to the study. Though this study will be hard to replicate today (due to IRB considerations), it wasn’t fully random, thus it’s a quasi-experiment, but it challenged and shocked the world. This is a pivotal paper/experiment that defined behavioral science.
- Creswell, J. W. (2013). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches, 4th Edition. [VitalSource Bookshelf version]. Retrieved from http://online.vitalsource.com/books/9781483321479/epubcfi/6/40
- Milgram, S. (1974) Obedience to Authority: The experiment that challenged human nature. New York: New York Times Company. Retrieved from: https://books.google.com/books/about/Obedience_to_Authority.html?id=vYGA45EODOgC&printsec=frontcover&source=kp_read_button&hl=en#v=onepage&q&f=false
- Pew Research Center (2015). Changing attitudes on Gay Marriage. Retrieved from http://www.pewforum.org/2015/07/29/graphics-slideshow-changing-attitudes-on-gay-marriage/