1. 47.269: Research I: The Basics Dr. Leonard Spring 2010
Basic Approaches to Empirical Research: Experimental vs. Non-experimental
47.269: Research I: The Basics
Dr. Leonard
Spring 2010

2. Beginning the research design
Empirical means based on systematic observation, or data collection
Involves determining who or what to study and how or when to study
Important to also explain why one wants to study a phenomenon (literature review -> theory -> hypothesis)
Can be quantitative or qualitative √
Can be experimental or non-experimental
Can be basic or applied research
Can be laboratory or field setting
Basic research: The goal is to increase understanding about a phenomena for the sake of gaining knowledge.
Applied research: The goal is to increase understanding of and find solutions to “real world” problems through research.

3. Beginnings of empiricism in psychology
Woodworth’s (1938) Experimental Psychology, a.k.a. the “Columbia bible”
Described accumulation of laboratory and experimental methods from beginning of the field of psychology when Wundt began conducting his “atoms of the mind” experiments
Focused on experiments related to the parts of psychology we now refer to as cognition, sensation, and perception
Clarified the distinction between experimental and non-experimental/correlational research we use today
First to use the terms independent variable and dependent variable as we use them today
Woodworth was trying to legitimize the science of psychology
Professor at Columbia
Research on sensation, perception, and intelligence – famous World Fair study in St. Louis – warned of inaccuracy of group averages in comparing intelligence of different races!
One of the early APA presidents
Wrote a lot about research methods

4. I.V. and D.V.
Independent variable is be manipulated or varied systematically while dependent variable can only be observed or measured
Independent variable is sometimes also called the predictor variable because it is used to predict some outcome in behavior
Dependent variable is sometimes also called the criterion variable because it is thought of s a standard being assessed
E.g., SAT scores used to predict college GPA
Pg. 11 in your text GPA is often the criterion by which SAT scores are judged to be valid.
Does anyone know how good of a predictor SAT scores are? How could we explaint his relationship?

5. Two major research designs
Experimental Design: Any scientific study in which the researcher systematically varies one or more variables, holding all others constant, to see if another variable is affected
In other words, does X cause changes in Y?
Non-experimental Design
Correlational Method: Any scientific study in which the researcher observes or measures (without manipulating) two or more variables to find relationships
In other words, are x and y associated?

6. Two major research designs
Key difference is degree of control of situation and means of data collection, or measurement
Experimental designs have more control
Experimental tends to collect data by measuring some concrete observation or effect after treatment
Non-experimental tends to collect data by observation or self-report (surveys)
BUT both often use same measures
Both could employ a quantitative or qualitative approach (majority of both are quantative!)
Both could be basic (for the sake of knowledge) or applied (seeking practical applications) research
Both could take place in a laboratory or field setting, though experimental is more often in laboratory
BOTH COULD USE SAME KINDS OF MEASUREMENT!

7. Pros and Cons?
Experimental designs can control effects of extraneous (outside) variables (+)
Experimental designs may produce artificial results or involve placebo effects (-)
Experimental designs require two variables that occur together or two comparable groups
Non-experimental designs are subject to the influence of extraneous variables (-)
Correlations might involve unseen “third variables”, indicating a spurious relationship, or directionality problems
Non-experimental designs can be used for prediction of future events (+)
Non-experimental designs can study a greater variety of variables (+)

8. Variations in Experimental designs
Treatment given to observe effects (causal)
If impossible to conduct experiment, may try a causal-comparative study (search for causes of already existing phenomena -- more non-experimental)
When might experimentation be impossible?
Independent variable must have two or more levels for comparison
Often accomplished by having experimental group(s) and control group (no treatment)
True experiment if assignment of participants to groups is random
Impossible for ethical or practical reasons…amount of cigarettes lung cancer example

9. Variations in Non-experimental designs
Goal is to capture attitudes and behaviors as they naturally occur
Can rely on researcher to observe participants or can ask participants to provide their own description (i.e., survey or interview)
Variables can be categorical (nominal, ordinal) or quantitative (interval, ratio)
Categories must be mutually exclusive and exhaustive so that all possible responses are accounted for
E.g., gender and voting preference; male-female are mutually exclusive, all candidates names plus an option for undecided would be exhaustive

10. Third option: Quasi-experimental designs
Occur more commonly in psychology
Apply experimental principles like cause and effect or group comparison to field, or less controlled settings
Less control over extraneous variables but can take place outside of lab, which may decrease the artificial feeling
Interpretation of results not as clean as in experimental research but closer to “real world” application

11. In-class activity
Working in groups, design an experimental study and a non-experimental study for the topic you have been given
Consider if each approach would be… quantitative or qualitative
basic or applied research
laboratory or field setting
Make sure to explain specifically how data would be collected and for what duration