Quantitative Research Designs

1. Quantitative Research Designs V. Darleen Opfer

2. Conditions for Establishing Cause-Effect Relationships: • Covariation • Temporal Precedence • No Plausible Alternative Explanations

3. History Testing Instrumentation Regression Mortality Maturation Selection Selection by maturation interaction Ambiguity about causal direction Diffusion of treatments Compensatory equalization of treatments Compensatory rivalry Types of Alternative Explanations

4. Ways to Minimize Threats to Validity: • By argument • By measurement or observation • By analysis • By preventive action • By design

5. Individual/Agential Variables Values Psychological Mechanisms Political Interest Personal Knowledge/ Experience Newspaper Coverage Newspaper Impacts Norms of Journalists Newspaper “Market Forces” Class, education, gender, ethnicity, age, etc.. Social Networks Trust in Media & Government (i.e., Public Schools) Structural/ Social Variables Causal relations Intervening variables

6. Basic Design Elements • Time • Program(s) or Treatment (s) = X • Observation(s) or Measure(s) = O • Groups or Individuals = R = Randomly assigned groups

7. An Example:

8. Expanding a Design:X O • Expanding across time O O X O O X O O X O • Expanding across programs O X1 O O X2 O • Expanding across observations O1O2 X O1O2 • Expanding across groups R O X O R O O N O O ______________________________ R O X O R O O N O O

9. A Strategy for Design Construction • Depict the hypothesized causal relationship • Identify the possible alternative explanation threats • Over-expand the basic design by expanding across time, program observations, and groups accounting for as many alternative explanations as possible • Scale back the design to a manageable plan by considering the effect of eliminating each design component

10. The Nature of Good Design • Theory-Grounded • Situational • Feasible • Redundant • Efficient

11. Design Task A principal/head teacher wants to know whether the provision of professional development will improve the instructional practices of teachers. Design a study for answering her question. Address the following questions: What are your variables? (What are will you be measuring?) What are potential validity/alternative explanation issues with this study? What are the validity issues accounted for in your approach? And how would you minimize those not accounted for in the design?