Quantitative Research Designs V Darleen Opfer Conditions for
- Slides: 11
Quantitative Research Designs V. Darleen Opfer
Conditions for Establishing Cause. Effect Relationships: n Covariation n Temporal Precedence n No Plausible Alternative Explanations
Types of Alternative Explanations n n n n History Testing Instrumentation Regression Mortality Maturation Selection by maturation interaction Ambiguity about causal direction n Diffusion of treatments n Compensatory equalization of treatments n Compensatory rivalry n
Ways to Minimize Threats to Validity: n By argument n By measurement or observation n By analysis n By preventive action n By design
Individual/Agential Variables Values Political Interest Psychological Mechanisms Personal Knowledge/ Experience Newspaper Coverage Newspaper Impacts Norms of Journalists Structural/ Social Variables Newspaper “Market Forces” Class, education, gender, ethnicity, age, etc. . Causal relations Intervening variables Social Networks Trust in Media & Government (i. e. , Public Schools)
Basic Design Elements n Time n Program(s) or Treatment (s) = X n Observation(s) or Measure(s) = O n Groups or Individuals = Randomly assigned groups
An Example: R O X O O
Expanding a Design: X O n Expanding across time n Expanding across programs O O X 1 O O X 2 O Expanding across observations O 1 O 2 X O 1 O 2 n Expanding across groups R O X O R O O N O O _______________ R O X O R O O N O O n
A Strategy for Design Construction n n 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
The Nature of Good Design n Theory-Grounded n Situational n Feasible n Redundant n Efficient
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: n. What are your variables? (What are will you be measuring? ) n. What are potential validity/alternative explanation issues with this study? n. What are the validity issues accounted for in your approach? And how would you minimize those not accounted for in the design?
