Summary of Foundations of Research Methods
Foundations of Research Methods: A Student's Guide
Introduction
Experimental design is the structured approach used to test a specific hypothesis by manipulating one factor and observing its effect while keeping other factors constant. This material explains core concepts, how to set up a simple consumer preference experiment, example procedures, variables and controls, and ethical considerations tailored for a Not attending student.
Definition: Experimental design is the plan for assigning treatments, controlling variables, and collecting data to test a specific hypothesis about cause and effect.
Key concepts broken down
1. Purpose of an experiment
- Determine whether changing one factor causes a measurable change in an outcome.
- Produce evidence that supports or refutes a hypothesis.
2. Independent variable (IV)
- The single factor you deliberately change in the experiment.
- Example: bottle material (plastic or glass).
Definition: The independent variable is the variable that the experimenter manipulates to observe its effect on the dependent variable.
3. Dependent variable (DV)
- The outcome you measure to see if the IV had an effect.
- Example: participant preference score, selection frequency, or purchase intention.
Definition: The dependent variable is the measurable effect or response that may change because of manipulations to the independent variable.
4. Constants (Controlled variables)
- Factors held the same across all experimental conditions so they do not influence the outcome.
- Examples: drink brand, volume, temperature, serving method, time of day, presentation environment.
Definition: Constants are variables kept the same across all groups to ensure a fair test of the independent variable.
5. Random assignment and control groups
- Randomly assign participants to conditions to reduce bias.
- A simple two-group design: Group A (plastic bottle) vs Group B (glass bottle).
6. Why only one independent variable?
- Having a single IV isolates cause-and-effect, avoiding confounding results from multiple factors changing at once.
- If you change multiple factors, you cannot tell which caused any observed difference.
Example experiment: Bottle preference study (step-by-step)
- Define the research question: Do customers prefer the drink in a plastic or glass bottle?
- Select participants: Recruit a representative sample of regular consumers of the drink (e.g., 100 people).
- Random assignment: Randomly assign participants to two groups of equal size.
- Prepare materials: Use the same drink, same volume (e.g., 330 mL), same temperature, identical labeling (if applicable) to avoid cue differences.
- Intervention: Serve the drink in plastic for Group A and in glass for Group B.
- Measurement: Ask participants to rate their preference on a standardized scale (for instance, 1–7) and record whether they choose the bottle again in a forced-choice task.
- Analyse data: Compare group means and proportions to see if preference differs significantly between bottles.
- Report: Present results with clear description of methods and limitations.
Practical measurement options (dependent variables)
- Preference rating (e.g., 1–7 scale).
- Choice frequency (which bottle they pick when both are available).
- Purchase intention (likelihood to buy if presented in that bottle).
- Reaction time or behavioural measures (e.g., first reach) for more subtle preferences.
Tables: Comparing related concepts
| Concept | Purpose | Example (bottle study) |
|---|---|---|
| Independent variable | Factor you change | Bottle material: plastic vs glass |
| Dependent variable | What you measure | Preference rating, choice frequency |
| Constants | What you keep same | Drink brand, volume, temperature, serving method |
| Random assignment | Reduce bias | Randomly assign participants to groups |
Controlling bias and variability
- Use random assignment to groups.
- Blind participants to study purpose wher
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Experimental Design Essentials
Klíčová slova: Research methods overview, Research design and classification, Qualitative research methods, Quantitative research, Experimental design, New product development
Klíčové pojmy: Independent variable: the one factor you change (e.g., bottle material)., Dependent variable: measurable outcome affected by the IV (e.g., preference rating)., Keep only one IV to avoid confounding effects., Constants must include drink brand, volume, temperature, and serving method., Use random assignment to reduce selection bias., Measure preferences with clear, standardized scales or choice tasks., Obtain informed consent, protect privacy, and minimize harm., Debrief participants if deception is used., Ensure sample size and representativeness for reliable results., Standardize instructions and environment to reduce variability