Research Methods and Study Design Flashcards
The Study: Key Components in Passages
- Topic
- Background
- Implications
- Scope of Research
- Differentiation Between Topic and Scope
- Hypothesis and Predictions
- Operational Definition of Variables
- Methods and Participants
- Results and Data
Steps to qualify a specific study design as an experimental design:
- Selection of Experimental and Control Groups
- Random Sampling from Population
- Random Assignment to Groups
- Control of Extraneous Variables
Experimental Designs
Directly manipulate variables
Experimental Design: 1. Selection of Experimental and Control Group
Treatment or Experimental Group
Placebo or Control Group
Experimental Design: 2. Random Sampling from Population
Sampling Population:
Random
Ideally: each individual in the population is equally likely to be sampled
BUT, reality: Most studies are done at Universities, thus University students are oversampled (introducing a potential internal flaw)
Experimental Design: 3. Random Assignment to Groups
Random: Selected individuals are equally likely be assigned to either of the two treatments.
Important that these assignments are double blind: neither the person placing people into groups not the participants know which group is which. (double blind is used to avoid the “placebo effect”)
Experimental Design: 4. Control of Extraneous Variables
Extraneous Variables: Variables other than the research variables that could potentially explain the finding.
What variables could potentially impact the results? Age, Gender, Ethnicity, Socio-economic, Education Level, and Severity of Depression.
- Researches should try to “control” for these variables so that individuals are equally distributed among groups.
- Impossible to account for every variable !
Benefit of Experimental Design:
Experimental designs are difficult to do but this design type (and only this design type) allows us to INFER a causal relationship
Two important types of validity (how well-done a study is):
Internal and External Validity
What is internal validity?
The extent to which we can say that the change in the outcome variable (or dependent variable) is due to the intervention.
A limitation of the study can be such that the experiment was not “well done”, leaving doubts about the conclusions because of some inherent flaw in the design.
What are common threats to internal validity?
Impression management Confounding Variables Lack of Reliability Sampling Bias Attrition Effects Demand Characteristics
Impression Management:
Participants adapt their responses based on social norms or perceived researcher expectations; self-filling prophecy; methodology is not double-blind, Hawthorne Effect
Confounding Variables:
Extraneous variables not accounted for in the study; another variable offers an alternative explanation for results; lack of a useful control
Lack of Reliability:
Measurement tools do not measure what they purport to, lack consistency
Sampling Bias:
Selection criteria is not random. Population used for sample does not meet conditions for statistical test (e.g. population is not normally distributed)
