Research Methods: Experimental designs and ethical guidlines

Week 2

How are experimental designs used in research?

Experimental designs are used to determine how participants are allocated to different conditions of an investigation. Help researchers control for extraneous variables and ensure that any changes in the DV are caused by the IV.

What are the strengths of the independent group design?

• No order effects: Participants only perform in one condition, so they do not become bored or practiced.

• Reduced demand characteristics: Due to participants only seeing one level of the IV, they are less likely to guess the aim of the study.

What are the limitations of the independent group design?

• Participant variables: Differences between individuals (e.g., IQ or age) may act as confounding variables.

• Participant economy: i#It requires twice as many participants as a repeated measures design to obtain the same amount of data points.

What are the strengths of the repeated measures design?

• Controlled participant variables: Same people are used in all conditions, eliminating individual differences.

• Fewer participants needed: Fewer people required for the study, making it more efficient (e.g., 10 participants provide 20 sets of data).

What are limitations of the repeated measures design?

• Order effects: The sequence of conditions can lead to practice effects (improvement) or fatigue effects (deterioration).

• Demand characteristics: Seeing both conditions makes it easier for participants to deduce the study's purpose and change their behaviour.

Describe counterbalancing to improve validity

Counterbalancing is a technique used to control order effects in repeated measures designs. Half the participants complete condition A then B, while the other half complete condition B then A (ABBA design). This ensures that any order effects are distributed evenly across both conditions.

What are the strengths of the matched pairs design?

• Reduces participant variables: Participants are matched on key characteristics (e.g., skill or personality) to make the groups comparable.

• No order effects: Each participant only takes part in 11 condition, so practice or fatigue is not an issue.

What are the limitations of the matched pairs design?

• Matching is difficult: It is time-consuming and expensive to find people who match perfectly on specific traits.

• Cannot match everything: Even with matching, it is impossible to account for every single participant difference.

What are the ethical guidelines/issues in researh?

1. Informed Consent: Ensuring participants know the aims and nature of the study.

2. Deception: Avoiding misleading participants unless absolutely necessary.

3. Protection from Harm: Participants should not suffer greater risk than in daily life.

4. Confidentiality: Keeping participant data private and anonymous.

5. Right to Withdraw: Participants must be able to leave the study at any time.