meadows quant res dese
TRANSCRIPT
Quantitative Research Design
Ken N. Meadows, Ph.D.
Educational Researcher
Teaching and Learning Services
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Outline Defining quantitative research design
Non-Experimental designs Descriptive Correlational
Experimental designs Experiments Quasi-experiments
Conclusions…
Definitions
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Research design: the framework used to conduct the research
Research method: data collection techniques (e.g., document analysis, interview, survey)
Definitions
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Quantitative research2,6:
Assumptions:
Reality - objective & singular
Researcher - independent from research
Research - value-free, unbiased
Research process – deductive (generate hypotheses from theory), emphasize cause/effect, isolation of variables, context-free, prediction, generalizability
Definitions
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Quantitative research2,6:
Methods: larger scale (e.g., survey)
Data: quantitative (numbers)
Analysis: statistical
Definitions
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Qualitative research2,6: Assumptions:
Reality – subjective & multiple (from participants’ perspective)
Researcher – interacts with research
Research – value-laden, biased
Research process – inductive (generate theory from data), emergent variables (identified during research), patterns identified
Definitions
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Qualitative research2,6:
Methods: smaller scale (e.g., interviews)
Data: qualitative (words)
Analysis: thematic
Definitions
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Two broad categories of quantitative designs:
Non-experimental Experimental
A major difference - validity of the designs7
Internal validity: extent design can identify causal relationships & rule out alternate explanations of relationships between variables
External validity: extent design allows conclusions to generalize beyond the confines of study
Definitions
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Non-experimental designs tend to be low in internal validity but higher in external validity
Experimental designs tend to be high in internal validity but lower in external validity
Non-experimental
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Non-experimental designs:
Descriptive Correlational
Descriptive designs5,7 - identify the characteristics of a phenomenon
Describe the variable under investigation –not examine relationships among variables
For example: LARSN needs assessment (Hoffman, Meadows, & Martin-Gardiner, 2009)
Non-experimental
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Correlational designs examine relationships among variables under investigation1,5,7
Tend to examine relationships as they exist
Do not isolate & manipulate variables to establish causal relationships as in experimental research
Non-experimental
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For example, Eron, Huesmann, Lefkowitz, & Walder (1972) examined relationship between preferences for violent television & aggressive behaviour
Non-experimental
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Cannot make causal statements with correlational research1,5,7
Directionality problem (if X <-> Y, does X ->Y or
Y ->X)
Third variable problem (if X <-> Y, possible
X<-Z->Y)
Non-experimental
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More complex correlational designs can suggest direction of causality
E.g., Cross-lagged panel correlation design
Eron and colleagues (1972) – collected data at grade 3 &13 and correlated variables between years – found moderate correlation between grade 3 preference for violent tv & grade 13 aggressive behaviour
Non-experimental
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In groups of 3, please discuss:
Research question you would be interested in researching
Design of your research (i.e., descriptive or correlational)
Data sources for that project
Research methods you would use
Experimental
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Experimental designs:
Experimental Quasi-experimental
Experiment1,3,5,7 - variable is systematically manipulated (independent variable; IV) to observe effect of manipulation on another variable (dependent variable; DV)
Experimental
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Experimental control1,3,5,7 – hold extraneous variables constant in experiment to isolate effect of IV on DV
For example, Hopkins & Wilson (2009)
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Experimental
Common experimental design: pre-test/post-test control group design1,3,5,7
Measure Before
Exposure Measure After
Treatment Group
01 X 02
Control Group 03 04
Experimental
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If change from pre- to post-test for treatment group & not control group (or not as much), change can be attributed to the treatment (assuming proper experimental controls)
Controlling for extraneous variables1,3,5,7:
Participant differences: random assignment of participants to treatment and control groups or matching
Situational differences: hold situations constant
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Experimental Pre-test/Post-test Control Group7 – possible pre-
test influences treatment (threat to external validity)
Post-test only control design7:
Exposure Measure After
Treatment Group
X 01
Control Group 02
Experimental
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Post-test only control group – groups should be same on DV before treatment because of random assignment
Other threats to external validity for experiments8:
Interaction effect of selection bias and treatment Reactive effects of the experiment
Experimental
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Quasi-experimental designs5,8: not true experiments because the groups tend to be naturally occurring not groups created by researcher
Try to match participants and control for situational variables as much as possible
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Experimental
Common quasi-experimental design: pre-test/post-test non-equivalent group design8
Measure Before
Exposure Measure After
Treatment Group
01 X 02
Control Group 03 04
Experimental
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Example: Haffie, Meadows, Dunn, & Graves (2009)
quasi-experimental research higher in external validity than experiments (reflect real life more) but weaker in internal validity than experiments (do not control for all extraneous variables) 8
Experimental
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In groups of 3, please discuss:
New research question you would be interested in researching
Design of your research (i.e., experimental or quasi-experimental)
Data sources for that project
Research methods you would use
References
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1. Bordens, K. S. & Abbott, B. B. (2008). Research design and methods: A process approach (7th ed.). Boston: McGraw-Hill.
2. Creswell, J. W. (1994). Research design: Qualitative and quantitative approaches. Thousand Oaks, CA: Sage Publications.
3. Elmes, D. G., Kantowitz, B. H., Roediger III, H. L. (1999). Research methods in psychology (6th ed.). Pacific Grove, CA: Brooks/Cole Publishing Company.
4. Eron, L. D., Huesmann, L. R., Lefkowitz, M. M. & Walder, L. O. (1972). Does television violence cause aggression? American Psychologist, 27, 253-263.
References
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5. Leedy, P. D., & Ormrod, J. E. (2001). Practical research: Planning and design (7th ed.). Upper Saddle River, N.J.: Merrill Prentice Hall.
6. O'Leary, Z. (2004). The essential guide to doing research. London: Sage.
7. Powell, R. R., & Connaway, L. S. (2004). Basic research methods for librarians (4th ed.). Westport, Conn.: Libraries Unlimited.