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DESIGNING PSYCHOLOGICAL RESEARCH

11.1.1 Identifying Variables

Understanding the key components of an experiment is crucial for establishing cause and effect.

IV

Independent Variable

The variable that the researcher manipulates or changes to observe its effect (the cause or input).
DV

Dependent Variable

What the researcher measures. It is the outcome or effect that may change due to manipulation of the IV.
EV

Extraneous Variables

Any variables other than the IV that might influence the DV. Controlling these is vital for valid, reliable conclusions. (Situational & Participant variables).

11.1.2 Controlling Extraneous Variables

Extraneous variables weaken reliability. Effective control measures secure the internal validity of the study.

S

Standardised Procedures

Ensuring every participant experiences exactly the same procedure (instructions, tasks, timing, environment).
C

Counterbalancing

Varies the order of conditions to control order effects (e.g., Half A then B; half B then A). Used in repeated-measures designs.
R

Randomisation

Randomly allocating participants to groups or randomising the order of conditions to eliminate systematic bias.
B

Blind Techniques

Single-blind (participant unaware of condition) prevents demand characteristics. Double-blind (neither participant nor researcher knows group allocation) prevents observer bias.

11.1.3 & 11.1.4 Hypothesis Formulation

Null Hypothesis (Hβ‚€)

The null hypothesis states there will be no effect or difference between groups or variables. Any observed changes are due to chance.

Example: There will be no difference in memory test scores between participants who sleep 4 hours and those who sleep 8 hours.

Alternative Hypothesis (H₁)

The alternative hypothesis predicts a specific effect or difference due to the IV. It can be directional (specifying the outcome) or non-directional.

Example: Participants who sleep 8 hours will have higher memory test scores than those who sleep 4 hours.

11.1.5 Random & Stratified Sampling

βœ…
StrengthsRandom: High generalisability (if sample large). Stratified: More representative of subgroups; maintains population characteristics.
❌
WeaknessesRandom: Difficult and time-consuming to access the entire population. Stratified: Complex, time-consuming, requires accurate population data.

Volunteer & Opportunity Sampling

βœ…
StrengthsVolunteer: Easy and quick to gather participants. Opportunity: Convenient and efficient (using readily available participants).
❌
WeaknessesVolunteer: Volunteer bias reduces generalisability. Opportunity: Likely to be unrepresentative and biased due to non-random selection.

11.1.6 Experimental Designs Comparison

Comparing Independent Measures and Repeated Measures designs.

βœ…
Independent Measures Strengths: No order effects (practice or fatigue).
Repeated Measures Strengths: Controls participant variables (person is own control); requires fewer participants.
❌
Independent Measures Weaknesses: Participant variables may affect results; needs larger samples.
Repeated Measures Weaknesses: Order effects (boredom/practice) influence scores; requires counterbalancing.
Matched Pairs Design: Participants are paired based on similar characteristics. Strengths: Controls participant variables without order effects. Weaknesses: Difficult and time-consuming to match perfectly.

11.1.7 Reliability vs. Validity

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How do quantitative and qualitative methods differ in validity?
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Quantitative (structured data) maintains validity but lacks richness. Qualitative provides rich, detailed data but is highly subject to researcher bias.
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And for reliability?
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Quantitative uses precise tools/repeat tests for consistency. Qualitative is difficult to replicate and is subject to researcher interpretation.

11.1.8 Managing Ethical Issues

Moral dilemmas must be managed to respect participant rights and psychological integrity.

1

Informed Consent

Participants must understand the research and agree voluntarily. Action: Provide clear information on aims and procedures before participation.
2

Deception

If used, it must be justified, cause minimal harm, and participants must be debriefed afterward.
3

Confidentiality / Privacy

Personal data must be kept private and anonymous. Action: Store data securely and report findings without identifying individuals.
4

Right to Withdraw & Protection

Participants can leave at any time without penalty. Safeguards against physical or psychological harm must be in place.

11.1.9 - 11.1.11 Experimental Settings

Lab Experiment (Controlled)

Features: Controlled environment; researcher manipulates IV and measures DV.
Strengths: High internal validity; easy to replicate.
Weaknesses: Low ecological validity (artificial); demand characteristics.

Field Experiment (Natural Setting)

Features: Conducted in a natural setting; researcher manipulates the IV.
Strengths: High ecological validity; behaviour more natural.
Weaknesses: Less control over extraneous variables; potential ethical issues if participants are unaware.

Natural Experiment (Observed)

Features: The IV changes naturally; researchers observe effect without intervention.
Strengths: Study unethical/impossible variables; high real-life relevance.
Weaknesses: Cannot randomly allocate; no control over extraneous variables; causality difficult to establish.

11.1.12 Interview Types (Structured vs Unstructured)

βœ…
Structured Strengths: Easy to replicate; data are comparable and quantifiable.
Unstructured Strengths: Detailed and rich data; explores participant experiences.
❌
Structured Weaknesses: Limited depth; may restrict responses.
Unstructured Weaknesses: Time-consuming; difficult to analyse systematically.

Semi-structured interviews offer a balance, allowing prepared questions with flexibility to explore new ideas.

11.1.13 Questionnaire Questions (Closed vs Open)

βœ…
Closed-ended Strengths: Easy to administer and quantify; good for statistical analysis and large samples.
❌
Open-ended Weaknesses: More difficult to analyse; may discourage some respondents (requires detailed input).

Closed questions generate quantitative data; Open questions provide rich, detailed qualitative data.

11.1.14 Correlation Pro Tip

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Correlation vs. Causation: Correlation measures relationships but does NOT imply causation. Third variables may always influence the relationship.

11.1.15 Case Study Focus

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Intensive Detail: Case studies provide in-depth understanding of one individual/group, useful for rare phenomena. Weakness: Highly subjective and not generalisable.

11.1.16 Observation Key

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Natural Behaviour: Observation records behaviour as it occurs (naturalistic or controlled). Strengths include rich data and real settings. Risk: Observer bias and ethical concerns if participants are unaware.

11.2.2 Measures of Central Tendency

These measures help summarize data sets for effective interpretation.

βˆ‘

Mean

The average value (sum of scores / number of scores). Good for data with no extremes.
↔

Median

The middle score when data are ordered. Useful when data have outliers.
#

Mode

The most frequent score. Helpful for categorical data.
Ξ”

Range

Difference between highest and lowest scores. Measures variability but sensitive to outliers.

11.2.3 Data Visualisation Types

Visual tools help identify patterns, trends, and outliers within data sets.

1

Frequency Tables

Summarise data, showing the number of occurrences per category.
2

Bar Charts

Represent categories with bars; used for discrete data.
3

Histograms

Represent continuous data with adjacent bars.
4

Scatter Diagrams

Plot pairs of values; useful to identify correlations.

11.2.4 Data Source Comparison

βœ…
Primary Data: Collected directly by the researcher for a specific purpose; more tailored to research questions.
❌
Secondary Data: Collected by others for different purposes; easier and quicker to access, but may be less relevant.

11.2.5 Data Type Comparison

βœ…
Qualitative Data: Descriptive and detailed, gives depth about behaviour, feelings, or experiences.
❌
Quantitative Data: Numerical, allowing statistical analysis and generalisation.

11.3.1 Core Ethical Imperative

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Goal of Guidelines: Ethical guidelines ensure research respects participant rights and wellbeing, safeguarding psychology’s reputation and scientific integrity.

Includes managing Informed Consent, Deception, Confidentiality, Right to Withdraw, and Participant Protection.

Designing Psychological Research Deck
Term
Independent Variable (IV)

What is an independent variable (IV)?

Answer
Definition

The variable that the researcher manipulates to observe its effect.

Term
Dependent Variable (DV)

What does the dependent variable (DV) represent?

Answer
Definition

The outcome measured to assess the effect of the IV.

Term
Extraneous Variables

Name two types of extraneous variables.

Answer
Examples

Situational variables and participant variables.

Term
Order Effects Control

What method controls order effects in repeated-measures designs?

Answer
Method

Counterbalancing.

Term
Null Hypothesis

Define a null hypothesis.

Answer
Definition

A statement predicting no effect or difference between groups or variables.

Term
Directional Alternative Hypothesis

What is a directional alternative hypothesis?

Answer
Definition

A hypothesis predicting the direction of the effect.

Term
Random Sampling

What is the main strength of random sampling?

Answer
Strength

Reduces sampling bias and increases representativeness.

Term
Main Experimental Designs

What are the three main experimental designs?

Answer
Designs

Independent measures, repeated measures, and matched pairs.

Term
Single-Blind Technique

How does a single-blind technique help research?

Answer
Purpose

Prevents participant bias by keeping them unaware of conditions.

Term
Informed Consent

What ethical principle requires participants to know the study’s purpose?

Answer
Ethical Principle

Informed consent.

Term
Laboratory Experiment Strength

Name one strength of laboratory experiments.

Answer
Strength

High internal validity due to control over variables.

Term
Qualitative vs Quantitative Data

What is the key difference between qualitative and quantitative data?

Answer
Difference

Qualitative is descriptive detail; quantitative is numerical data.

Term
Situational Variables Effect

What is the effect of situational variables?

Answer
Effect

They can unintentionally influence participant behaviour.

Term
Double-Blind Technique

When is double-blind technique used?

Answer
Usage

To prevent both participant and researcher biases.

Term
Volunteer Sampling

What sampling method involves participants selecting themselves?

Answer
Method

Volunteer sampling.

Term
Median

What does the measure of central tendency 'median' represent?

Answer
Definition

The middle score in an ordered dataset.

Term
Structured Interview

What kind of interview uses a fixed set of questions?

Answer
Type

Structured interview.

Term
Randomisation

Why is randomisation important in research?

Answer
Importance

Eliminates systematic bias in participant allocation or condition order.

Term
Ecological Validity

What does ecological validity refer to?

Answer
Definition

How well study findings generalise to real-world settings.

Term
Confidentiality

What ethical issue involves keeping participant data private?

Answer
Ethical Issue

Confidentiality.

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🧠 Designing Psychological Research Quiz

1. Which of the following is an extraneous variable?

Noise is a situational extraneous variable that can influence participant behaviour and the DV.

2. What is the main purpose of counterbalancing in repeated-measures designs?

Counterbalancing changes the order of conditions to prevent fatigue or practice effects skewing results.

3. A null hypothesis predicts a specific direction of effect. (True or False)

Null hypotheses predict no effect or difference; directional predictions belong to the alternative hypothesis.

4. Which sampling technique involves selecting participants who are easiest to reach?

Opportunity sampling uses readily available participants but is prone to bias.

5. Which research design uses different participants in each experimental condition?

Independent measures designs assign different participants to each condition, avoiding order effects.

6. Which ethical principle requires participants to voluntarily agree to take part after understanding the study?

Participants must be given clear information to voluntarily consent to participation.

πŸ“Š Results

  • Notes and Quiz
  • Psychology
  • GCSE
  • Research Methods
  • EDEXCEL