Experimental Design - Research Methods [A-Level Psychology]

Psych Boost
24 Jan 202205:31
EducationalLearning
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TLDRThis video script introduces two fundamental experimental designs in psychology: the independent groups design, which uses separate samples for each condition, and the repeated measures design, where participants complete all conditions. The former is vulnerable to participant variables, while the latter can suffer from order effects. The script also discusses counterbalancing to control order effects and the matched pairs design to mitigate these issues. It concludes with a mention of tutorial videos and resources for further learning on research methods.

Takeaways
  • 🔬 The video discusses two primary experimental designs in psychology: repeated measures and independent groups.
  • 📚 In a repeated measures design, the same participants complete both conditions of the experiment, allowing for comparison of their performance across conditions.
  • 🧑‍🤝‍🧑 Independent groups design involves different sets of participants for each condition, with data from one group compared to another, creating unrelated data.
  • 👀 A potential issue with the independent groups design is that differences measured may be due to participant variables rather than the independent variable.
  • ⏱️ Repeated measures design can control for participant variables but may introduce order effects, such as practice or fatigue influencing results.
  • 🎯 Counterbalancing can be used to mitigate order effects by having participants complete conditions in different orders.
  • 📉 Independent groups design requires more participants than repeated measures to achieve equivalent data volume.
  • 🤔 Repeated measures may suffer from demand characteristics, where participants alter their behavior to please the researcher.
  • 🔄 Matched pairs design is introduced as a solution to control for both participant variables and order effects by using pairs of similar participants.
  • 📈 Matched pairs design involves ranking participants by a characteristic that may influence results and then assigning them to conditions to balance this characteristic.
  • 📝 The video also mentions the resources available on psychboost.com for further study and the support from Patreon for the development of educational content.
Q & A

  • What is the main topic of the video script?

    -The main topic of the video script is experimental design in psychology research, focusing on different types of experimental designs and their advantages and disadvantages.

  • What are the two basic experimental designs mentioned in the video?

    -The two basic experimental designs mentioned are the repeated measures design and the independent groups design.

  • What is an independent groups design and how does it work?

    -An independent groups design is a research setup where different sets of participants complete different conditions of an experiment. The data collected from one group is compared with the data from another group, and this type of data is called unrelated data.

  • What potential issue can arise in an independent groups design?

    -In an independent groups design, a potential issue is that any measured change may not be due to the independent variable but could be influenced by participant variables or characteristics of the people taking part.

  • What is a repeated measures design and why is it used?

    -A repeated measures design is used when all participants complete both conditions of the experiment. It is used to control for individual differences by comparing each participant's score in one condition with their score in the other condition, thus collecting related data.

  • What is the main problem with a repeated measures design?

    -The main problem with a repeated measures design is the potential for order effects, where participants may perform differently in the second condition due to factors like practice, boredom, or fatigue.

  • How can order effects be controlled in a repeated measures design?

    -Order effects can be controlled by counterbalancing, which involves having half of the participants do condition A then B, and the other half do B then A, to balance the influence of order effects across conditions.

  • What is a matched pairs design and how does it differ from the other two designs?

    -A matched pairs design uses two separate groups of participants for each condition, matched on a characteristic that may influence the results, such as IQ or age. This design reduces the effect of participant variables and order effects by ensuring participants are similar and only take part in one condition.

  • What are some disadvantages of using a matched pairs design?

    -Disadvantages of a matched pairs design include the need for more time to set up the matching process, the requirement for more participants to produce the same amount of data compared to repeated measures, and the fact that participants are similar but not identical, which may still introduce some participant variables.

  • What does the video script suggest about the relationship between the strengths and weaknesses of the two basic experimental designs?

    -The video script suggests that the strengths of one design are the weaknesses of the other, indicating a trade-off between the two in terms of controlling for participant variables and order effects.

  • What additional resources are mentioned in the video script for further learning?

    -The video script mentions 6 tutorial videos covering the 2017, 18, and 19 AS and A-level research methods sections, which include worked examples and exam tips, available to patrons at the neuron level and above on psychboost.com.

Outlines
00:00
🔬 Experimental Design Overview

This paragraph introduces the topic of experimental design in psychology, focusing on how researchers use participant samples and manipulate independent variables. It discusses the importance of choosing the right design and the trade-offs involved. The speaker plans to cover two main types of experimental designs: repeated measures and independent groups. The independent groups design involves different sets of participants for each condition, leading to unrelated data that can be affected by participant variables. The repeated measures design has participants complete both conditions, resulting in related data but potential order effects. The paragraph also touches on counterbalancing as a method to control order effects and the challenges of each design, such as the need for more participants in independent groups and the risk of demand characteristics in repeated measures.

05:05
🙌 Community Support and Future Content

The second paragraph expresses gratitude to the students and teachers who have supported the development of the research methods unit through Patreon. This support has enabled the speaker to teach part-time and create content for psych boost on YouTube. The speaker also hints at upcoming videos on research methods and mentions the availability of tutorial videos, worked examples, and exam tips for patrons at the neuron level and above on psychboost.com. The paragraph concludes with a note of thanks and an anticipation for the next video in the series.

Mindmap
Keywords
💡Experimental Design
Experimental design refers to the methodological framework within which an experiment is conducted. It is crucial for ensuring the validity and reliability of the results. In the video, experimental design is the central theme, focusing on how researchers can structure their experiments using different participant samples and levels of independent variables. The script discusses the advantages and disadvantages of various designs to help viewers understand which might be most appropriate for their research.
💡Participant Sample
A participant sample is a group of individuals chosen to take part in an experiment. The selection of this sample is critical as it can influence the outcomes and generalizability of the study. The video mentions how researchers have choices in setting up their experiments with different participant samples, which can impact the results due to variables such as age, IQ, or other characteristics.
💡Independent Variable
The independent variable is the element that researchers manipulate in an experiment to observe its effect on the dependent variable. It is 'independent' in the sense that it is not affected by other variables in the experiment. The script explains how researchers use different levels of the independent variable to understand its impact on the behavior or performance of participants.
💡Repeated Measures Design
A repeated measures design is an experimental setup where all participants complete both conditions of the experiment. This design allows for the comparison of a participant's performance under different conditions, using related data. The video script uses this concept to illustrate how order effects, such as practice or fatigue, can influence the results, and how counterbalancing can help control for these effects.
💡Independent Groups Design
This design involves randomly splitting the participant sample into separate groups for each experimental condition. Each group is independent, meaning the data collected from one group is unrelated to the data from another. The script points out the potential issue of participant variables influencing the results, as the groups may differ in systematic ways unrelated to the independent variable.
💡Unrelated Data
Unrelated data is collected when each group in an experiment is independent of the others, as in the independent groups design. The video script explains that this type of data can be problematic because differences measured between conditions might be due to participant characteristics rather than the independent variable.
💡Related Data
Related data is used in a repeated measures design, where each participant's performance in one condition is compared to their performance in another condition. The script emphasizes the importance of related data in statistical testing, as it allows for the examination of within-subject effects and controls for individual differences.
💡Order Effects
Order effects refer to changes in a participant's performance due to the sequence in which conditions are presented. The video script discusses how participants might improve or decline in performance in the second condition because of factors like practice or fatigue, and how counterbalancing can help mitigate these effects.
💡Counterbalancing
Counterbalancing is a technique used to control for order effects in a repeated measures design. The script explains that by having half of the participants complete the conditions in one order and the other half in the reverse, researchers can balance the potential influence of order effects across conditions.
💡Matched Pairs Design
A matched pairs design is an experimental setup where two separate groups of participants are matched on a characteristic that may influence the results, such as age or IQ. The script describes how this design can reduce the impact of participant variables and order effects by ensuring that each pair of participants is similar and only completes one condition.
💡Demand Characteristics
Demand characteristics are aspects of an experiment that may lead participants to change their behavior in order to please the researcher or fulfill their expectations. The video script mentions this as a potential issue in repeated measures designs, where participants completing both conditions might deduce the experiment's aims and adjust their responses accordingly.
Highlights

Introduction to experimental design in psychology research methods.

Two fundamental experimental designs: repeated measures and independent groups.

Repeated measures design involves all participants completing both conditions.

Independent groups design splits the sample randomly into two groups for different conditions.

Unrelated data is collected in independent groups design, comparing different sets of people.

Potential issue with independent groups design is the influence of participant variables on results.

Repeated measures design uses related data, comparing a participant's score across conditions.

Order effects are a concern in repeated measures design due to participants completing both conditions.

Counterbalancing is used to control order effects in repeated measures design.

Independent groups design requires more participants for the same amount of data.

Repeated measures design risks demand characteristics as participants may alter behavior.

Matched pairs design addresses issues of participant variables and order effects.

Matched pairs design involves ranking participants by a characteristic and assigning them to conditions.

Related data is used in matched pairs design, comparing results within pairs.

Matched pairs design reduces the effect of participant variables and eliminates order effects.

Disadvantages of matched pairs design include setup time, participant number requirements, and potential remaining participant variables.

Tutorial videos and resources for AS and A-level research methods are available on psychboost.com.

Support from Patreon helps in the development of the research methods unit.

Transcripts

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Related Tags
Experimental DesignPsychology ResearchParticipant SampleIndependent VariableRepeated MeasuresIndependent GroupsOrder EffectsCounterbalancingMatched PairsResearch Methods