How to Know if a Quantitative Research Design Is Appropriate for Your Study
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The document provides an overview of quantitative research design, discussing its characteristics, when it is appropriate, and various types of designs, including pre-experimental, experimental, and quasi-experimental. Each design type is described with basic diagrams and potential threats to validity outlined. Additional resources and coaching information for doctoral work are also mentioned.
How to Know if a Quantitative Research Design Is Appropriate for Your Study
- 1. Thanks for Coming We will start in just a moment
- 2. How to Know if a Quantitative Research Design Is Appropriate for Your Thesis
- 3. Taken from: Wiersma, W. & Jurs, S.G. (2009). Research methods in education: An introduction (9th ed.). Boston, MA: Allyn and Bacon Characteristics of Quantitative Research • Deductive • Look for relationships, effects, causes • Theory-based • Focused on individual variables • Context- free (Generalizations) • Detached role of researcher • Statistical analysis (Wiersma & Jurs, 2009, p. 15)
- 4. When to Choose Quantitative Research If you are interested in: • Determining relationships, effects, and/or causes • Testing theories, models, approaches (even if that is not an explicit goal of the study, but theoretical principles are important in one way or another)
- 5. Types of Quantitative Research Designs • Pre-experimental: Little or no control • Experimental: High degree of control • Quasi-experimental: Minor level of control because random selection or assignment is not possible. Statistics is used to improve the control of variables
- 6. Pre-Experimental Designs • Case study • One group pretest – posttest • Static group comparison or cross-sectional
- 7. Case Study Design • Description: One group is studied after applying a treatment or intervention • Diagram: X O2 X = Treatment O2 = Posttest • Threats to validity: Little or no control of the effect of variables, history, maturation, selection, mortality, and interaction effects of selection biases and the experimental treatment
- 8. One Group Pretest-Posttest Design • Description: The dependent variable is measured, the treatment or intervention is applied, and the dependent variable is measured again • Diagram: O1 X O2 O1 = Pretest X = Treatment O2 = Posttest • Threats to validity: History, maturation, instrumentation, mortality, selection- maturation interaction, reactive effect of testing, and interaction effects of selection biases and the experimental treatment
- 9. Static Group Comparison or Cross- Sectional Design • Description: A group to which a treatment has been applied is compared to another group that has not experienced it • Diagram: X O2 X = Treatment O2 = Posttest -‐-‐ O2 • Threats to validity: Selection, mortality, reactive effect of testing, and interaction effects of selection biases and the experimental treatment
- 10. Experimental Designs • Randomized posttest groups • Pretest- posttest control group • Solomon four groups • Factorial
- 11. • Descrip(on: Two groups are compared using pos@est and random assignment of subjects and treatment to control prior differences • Diagram: R X O2 R = Randomization X = Treatment O2 = Posttest R -‐ O2 • Threats to validity: The change of the experimental group cannot be measured Randomized Posttest Groups Design
- 12. • Description: Two groups are compared using pretest and posttest and random assignment of subjects and treatment • Diagram: R O1 X O2 R = Randomization O1 = Pretest X = Treatment O2 = Posttest R O1 - O2 • Threats to validity: Reactive effect of testing Pretest –Posttest Control Group Design
- 13. • Description: To address the reactive effect of testing, two control groups are added to the pretest-posttest control group design; one without taking pretest and another one without pretest and treatment • Diagram: R O1 X O2 R O1 - O2 R - X O2 R - - O2 R = Randomization O1 = Pretest X = Treatment O2 = Posttest • Threats to validity: None by itself Solomon Four Groups Design
- 14. • Descrip(on: The different levels of two or more independent variables (factors) are considered to establish not only their effects on the dependent variable but also the ones caused by the interacMon among them • Diagram: R X11 O (Notation of a 2 X 2 factorial design) R X12 O R X21 O R X22 O R = Randomization X11 = Factor 1, level 1 X12 = Factor 1, level 2 X21 = Factor 2, level 1 X22 = Factor 2, level 2 O = Measurement • Threats to validity: None by itself Factorial Design
- 15. Quasi-Experimental Designs • Nonrandomized pretest-posttest control group • Counterbalanced • Time series
- 16. • Description: Two groups are compared using pretest and posttest. There is not random assignment of subjects since they are already in groups • Diagram: O1 X O2 O1 = Pretest X = Treatment O2 = Posttest O1 - O2 • Threats to validity: Selection, statistical regression, and reactive effect of testing Non Randomized Pretest –Posttest Control Group Design
- 17. • Description: The order in which treatments are administrated is changed during the study so as to test every subject for all the considered conditions • Basic Diagram : G1 XA XB O G2 XB XA O X = Treatment G = Group O = Measurement • Threats to validity: Multiple treatment interference Counterbalanced Design
- 18. • Description: The dependent variable is measured several times before applying a treatment and then a new series of measurement is performed • Diagram : O1 O2 … X Oi… On X = Treatment O = Measurement • Threats to validity: History and reactive effect of testing Time Series Design
- 19. Now you know: Any question? 1. Characteristics of quantitative research 2. When to choose quantitative research 3. Types of quantitative research designs 4. Description, basic diagram, and threats to validity of each type of design
- 20. February is Coaching Month • Each week will introduce and focus on a different coach • Lots of new helpful hints per phase of doctoral work • Additional videos in the interviews • Ask questions during webinars • Members have professors on Skype I invite you to read: My professor hints about coaching at http://doctoralnet.com/maria.html The challenges of each phase at: http://doctoralnet.com/starting-phd-research/phase-1-files/professor- hints/item/825-maria-sanchezphase1.html (phase 1) http://doctoralnet.com/beginning-to-write-phd-thesis/professor-hints- phase-2/item/827-maria-sanchezphase2.html (phase 2) http://doctoralnet.com/finishing-phd-thesis/professor-hints-phase-3/ item/828-maria-sanchezphase3.html (phase 3) And my interview at http://doctoralnet.com/home/about-us/interview-with-prof-maria- sanchez-patino.html
- 21. What’s Up 4 Free @ DoctoralNet.com? 1. Community 2. Blog 3. 365 Daily InspiraMons 4. Your personal milestone checklist – free but requires site basic registraMon 5. Want these slides? Ask for them at maria@doctoralnet.com