Sampling - Research Methods [A-Level Psychology]

Summary

This video explores various sampling techniques in psychological research, including Random, Systematic, Stratified, Opportunity, and Volunteer sampling. It discusses the importance of representative samples for generalizing findings to the wider population and the potential biases associated with each method. The video also addresses WEIRD participant bias and its implications for the global applicability of psychological research.

Takeaways

• 🔍 The video discusses the importance of sampling in psychological research and the need to consider whether findings can be generalized to the wider population.
• 🎯 The target population is defined as every individual that forms part of the group being studied, and researchers aim to generalize results from samples back to this population.
• 📈 Five sampling techniques are introduced: Random, Systematic, Stratified, Opportunity, and Volunteer, each with its own strengths and weaknesses.
• 🎰 Random sampling ensures every member of the population has an equal chance of being selected, which helps to avoid researcher bias.
• 🔢 Systematic sampling involves selecting members at regular intervals from a list, which is quick but can still potentially lead to unrepresentative samples.
• 👥 Opportunity sampling is the most accessible method, using readily available participants, but it is prone to researcher bias and may not be representative.
• 🙋 Volunteer sampling, where participants self-select, can reach a large audience but suffers from volunteer bias, as it may not include a diverse range of individuals.
• 🏛 Stratified sampling is the most complex and aims to create a sample that mirrors the population's subgroups, which helps in generalizing findings accurately.
• 🌐 The concept of 'WEIRD' participants (Western, Educated, Industrial, Rich, and Democratic) is highlighted as a potential bias in psychological studies, questioning the global applicability of research findings.
• 👩‍🏫 Historical studies are criticized for often ignoring or underrepresenting women, leading to considerations of gender bias in psychological theories.
• 📚 The video concludes by promoting tutorial videos and resources for further study on research methods in psychology.

Q & A

What is the importance of sampling in psychological research?

Sampling is crucial in psychological research because it allows researchers to study a subset of a larger population, which is often impractical to test in its entirety. The goal is to obtain a sample that is representative of the population to ensure that the findings can be generalized.

What are the five sampling techniques discussed in the video?

The video discusses five sampling techniques: Random, Systematic, Stratified, Opportunity, and Volunteer sampling.

How does random sampling work and what are its strengths and weaknesses?

Random sampling involves selecting participants from a population such that each member has an equal chance of being chosen. This method avoids researcher bias but can sometimes result in an unrepresentative sample, especially if the population is large.

What is systematic sampling and how does it differ from random sampling?

Systematic sampling involves selecting members from a list at a regular interval, such as every 5th or 10th person. It is similar to random sampling but differs in the selection process, which is more structured. It also removes researcher bias but can be prone to the same issues of unrepresentativeness as random sampling.

Why is opportunity sampling a common method in psychological studies?

Opportunity sampling is common because it is the easiest and fastest way to obtain a sample. Researchers simply include anyone they can easily access, often leading to studies being conducted on university students. However, it can introduce researcher bias and may not be representative of the wider population.

What is a volunteer sample and what are the potential biases associated with it?

A volunteer sample, also known as a self-selecting sample, consists of individuals who choose to participate in a study. While it can reach a large number of participants, it introduces volunteer bias because those who volunteer may not represent the wider population, often being more motivated or having more time to participate.

How does stratified sampling aim to overcome the limitations of other sampling methods?

Stratified sampling creates a sample that is representative of the population by first identifying subgroups (strata) and their proportion in the population. Participants are then randomly selected from each strata to ensure the sample mirrors the population's composition. This method reduces bias and increases the confidence in generalizing the findings.

What is the criticism of psychology studies regarding the term 'WEIRD' participants?

The term 'WEIRD' refers to the fact that many psychology studies have been conducted on participants from Western, educated, industrial, rich, and democratic backgrounds. This leads to questions about the applicability and generalizability of psychological findings to diverse populations worldwide.

What is the role of generalization in psychological research?

Generalization in psychological research refers to the ability to apply the findings from a sample back to the target population. It is a critical aspect of research as it allows researchers to make broader claims about the population based on the study's results.

How does the video script address the issue of gender bias in historical psychological studies?

The script mentions that historical studies often ignored or underrepresented women, leading to potential gender bias in accepted psychological theories. This highlights the importance of considering diverse samples in research to avoid such biases.

Outlines

00:00

🔍 Introduction to Sampling Techniques in Psychology Research

This paragraph introduces the concept of sampling in psychological research, emphasizing the importance of selecting a representative sample to ensure that study findings can be generalized to the broader population. The paragraph outlines five sampling techniques: Random, Systematic, Stratified, Opportunity, and Volunteer. It also highlights the need to consider the strengths and weaknesses of each method. The target population is defined as the entire group that a researcher plans to study, and the goal is to select a sample that accurately represents this population. The concept of generalization, where results from a sample are applied back to the target population, is discussed, along with the challenges of achieving representativeness due to the variability within populations.

05:00

📊 Exploring Different Sampling Techniques and Their Implications

This paragraph delves into the specifics of each sampling technique, discussing how they work and their respective advantages and disadvantages. Random sampling is described as a method that gives every individual in the population an equal chance of being selected, which helps to avoid researcher bias but may sometimes result in an unrepresentative sample. Systematic sampling involves selecting members at regular intervals from a list, which is efficient but can also lead to unrepresentative samples if not carefully managed. Opportunity sampling is the most accessible method, where researchers include whoever is available, which is fast but prone to researcher bias and often not representative. Volunteer sampling, where participants self-select, can reach a large audience but suffers from volunteer bias, as those who volunteer may not be representative of the wider population. Stratified sampling is the most complex method, aiming to create a sample that mirrors the population's subgroups, which helps in generalizing findings but can be time-consuming and may introduce bias in the selection of strata.

Keywords

💡Sampling

Sampling refers to the process of selecting a subset of individuals from a larger population for the purpose of a study. In the context of the video, sampling is crucial as it affects the generalizability of research findings. The script discusses various sampling techniques, emphasizing the importance of choosing a method that best represents the population to ensure the study's validity.

💡Target Population

The target population is the entire group that researchers aim to study. It is defined as every individual that forms part of the group of interest. For instance, if a researcher is studying pensioners, the target population would include all pensioners. The script mentions that it is often impractical to study the entire target population, necessitating the selection of a sample.

💡Generalisation

Generalisation is the process of applying the findings from a sample back to the target population. The video script stresses the importance of having a representative sample to ensure that the results can be generalized. This concept is central to research methodology in psychology, as it determines the extent to which findings can be applied to a broader context.

💡Random Sampling

Random sampling is a technique where every member of the population has an equal chance of being selected for the study. The script illustrates this with the example of drawing names from a hat or using a random number generator. This method is highlighted for its strength in avoiding researcher bias, ensuring that the selection process is unbiased and fair.

💡Systematic Sampling

Systematic sampling involves selecting members from an ordered list at regular intervals. The script uses the analogy of a teacher picking every third name from a class register. This method is efficient and reduces researcher bias, but like random sampling, it can still result in an unrepresentative sample if not done carefully.

💡Opportunity Sampling

Opportunity sampling is a non-probability sampling method where researchers select participants based on availability. The script points out that this method is fast and cost-effective but is prone to researcher bias and may not yield a representative sample, often leading to studies being conducted on easily accessible populations like university students.

💡Volunteer Sampling

Volunteer sampling, also known as self-selecting sampling, involves participants who choose to take part in a study. The script mentions that while this method can reach a large audience through advertisements, it suffers from volunteer bias, as those who volunteer may not be representative of the wider population, potentially skewing the study's results.

💡Stratified Sampling

Stratified sampling is a complex method that involves dividing the population into subgroups or strata and then randomly selecting samples from each stratum. The script explains that this method aims to ensure that the sample is representative of the population, thus increasing the confidence in generalizing the findings. However, it can be time-consuming and may introduce bias in the selection of strata.

💡Bias

Bias in the video script refers to any factors that systematically lead to inaccuracies or distortions in the study's results. The script discusses various types of bias, including researcher bias and volunteer bias, and how different sampling methods can either introduce or mitigate these biases. Understanding and managing bias is critical for the validity of psychological research.

💡WEIRD Participants

The term 'WEIRD' refers to participants from Western, Educated, Industrial, Rich, and Democratic backgrounds. The script criticizes the overrepresentation of WEIRD participants in psychological studies, suggesting that much of psychological knowledge may not generalize well to other cultures or demographic groups. This term is used to highlight the importance of diversity in research samples.

Highlights

The importance of considering who participates in a study and if their behavior can be generalized to everyone.

Introduction to five sampling techniques: Random, Systematic, Stratified, Opportunity, and Volunteer.

Definition of the target population and the concept of generalization from a sample back to the population.

The process and benefits of random sampling to avoid researcher bias.

Challenges with random sampling, such as the potential for unrepresentative samples and time-consuming nature with large populations.

Systematic sampling method and its similarity to random sampling with a fixed interval selection.

Advantages of systematic sampling, including speed and reduced researcher bias.

Opportunity sampling as the easiest and fastest method but with potential for researcher bias and unrepresentative samples.

The concept of volunteer sampling and its reliance on self-selection of participants.

Concerns with volunteer bias and the challenge of generalizing findings from volunteer samples.

Stratified sampling as a complex method aiming for representativeness of the population.

The benefits of stratified sampling in ensuring representativeness and avoiding researcher bias.

Challenges with stratified sampling, including the potential for bias in strata selection and the time-consuming process.

Critique of psychology studies focusing on WEIRD (Western, Educated, Industrial, Rich, and Democratic) participants.

The implications of WEIRD participant bias on the generalizability of psychological findings globally.

Historical gender bias in psychological studies and its impact on accepted theories.

Resources available for further study on research methods in psychology.

Acknowledgment of supporters and the role of community in developing educational content.

Transcripts

This research methods in psychology video is  Sampling. When researchers conduct studies,  

and then publish findings it's tempting to think  the findings apply to all of us. But we need to  

think carefully about who exactly took part in the  study, and if the behaviour of those participants  

can be genralised to everyone. So in this video we  will be looking at 5 sampling techniques Random,  

Systematic, Stratified, Opportunity and Volunteer.  We will of course also consider the strengths and  

weaknesses of each. INTRO 

Our first definition is for the term target  population, this is every individual that forms  

part of the group you plan to study. So likely to  be a very large number, if you are investigating  

pensioners, or four year old children, or sixth  form students we won't be able to test all of  

them, we need to take some of them, a sample.  What we hope to do when we get our results  

from the sample, is apply the results back to the  target population, this is called generalisation.  

However, members of a population vary in many  ways, so ideally we want a sample that is  

representative of the larger population. Random 

So let's start with random sampling, now it's not  just grabbing anyone to take part in your study,  

it's mathematically random, so everyone  in the population has the same chance or  

probability to be selected as a member of  the sample. A researcher first needs a list  

of all members of the population. And then use  a method of selecting them randomly. So putting  

the names into a hat and drawing them out until  they have a full sample, or giving each name a  

number and using a random number generator. The strength of this method is it avoids  

researcher bias. The researcher can’t just  choose the people they want in the study,  

which could influence the results. However because it is random,  

we could randomly get an unrepresentative sample,  maybe not representing all minority groups. 

If the population size is large a  random sample can be time consuming, 

Systematic Systematic sampling is similar to random, we  

still need the list of the population, but instead  of picking randomly, we go down the list and  

choose every 5th or 10th or Nth person. You can  imagine a teacher picking a sample from her class  

using the register and calling out every 3rd name. This again removes the chance for researcher bias  

in picking who they want in their studies. And  with a small population studied, and lists of the  

population already exist, such as with the  register can be a quick way of getting a sample 

It's unlikely but still possible to to  get an unrepresentative sample using a  

systematic approach, and with large populations  it's difficult to get a full list of members. 

Opportunity An opportunity  

sample is the easiest sample to get and most  commonly used. The researcher simply includes  

anyone in the sample that they can get their  hands on by simply asking them to take part.  

For that reason many psychology studies are  actually conducted on university students. 

A strength of this of course is it's a  much faster way of getting a sample than  

other methods. This could save money and allow  the researcher to complete the study faster. 

But there are big problems with an opportunity  sample. There is the potential for researcher  

bias. The researcher decides who to ask and  who not to ask, potentially manipulating  

the results. Also the sample is likely not  representative as the researcher only has  

access to a limited section of the population,  in most cases, young university students. 

Volunteer Another word for a volunteer sample  

is a self selecting sample. This makes clearer  the important factor of this sampling method,  

that the participants select themselves  , they volunteer themselves. They are not  

directly asked. So they may see an advert in the  newspaper or online and put themselves forward. 

So a strength of this is by using an  advertisement, especially in a popular newspaper,  

the researcher can reach a large number of  potential participants. And is relatively  

easy to collect as after placing the ad, the  participants are putting themselves forward.

but we have the issue of volunteer bias,  people who volunteer for studies are a  

certain type of person. They are of course  helpful, and they have the time to take  

part in psychology studies. But we want to  include people who are unhelpful, and people  

who are busy. If we don't we may not be able to  generalise our findings to the wider population. 

Stratified A stratified sample is the most  

complex type of sample, but it tries to avoid some  of the problems of the other methods. A stratified  

sample creates a sample that is representative  of the population as a whole. So firstly the  

researcher will identify subgroups, or strata  and their proportion in the wider population. 

Then the sample is made by randomly selecting  participants from within each strata  

so they are represented in the same population  in the final sample. So if 10% of your population  

were university graduates, 10% of your  sample would be university graduates. 

The big positive of this approach to sampling  is the sample is representative of the larger  

population, meaning we can be confident in  genralising what we find to the population. 

Also this sampling method avoids  researcher bias as it randomly  

selects participants from within each strata. But the researcher does decide what strata are  

important to consider, meaning there may  be some bias in the selection of strata,  

and as you can imagine stratified  sampling is time consuming and difficult. 

Bouns fact - WEIRD participants So when considering sampling we  

need to consider the implications of bias  and generalisation. I've already told you  

what genralisation is and about researcher bias  and volunteer bias. But going a little deeper,  

a critisicm of psychology studies is most of  them have been completed on WEIRD participants. 

And by weird I mean most participants  of from a western, educated, industrial,  

rich and democratic background. In fact if you  are an American university student you are 4000  

times more likely to be in a psychology study  than a random non westerner. This leads us to  

consider if much of what we know about psychology  actually applies, or genralises around the world. 

Also the samples of historical studies,  often ignored or underrepresented women,  

leading us to also consider gender bias  in much of accepted psychological theory. 

Outro So that was Sampling,  

I have 6 tutorial videos covering the 2017,18  and 19 AS and A-level research methods sections,  

these videos have worked examples to every  question and are full of exam tips. Patrons  

at the neuron level and above can access these,  and many, many more hours of exam tutorial videos,  

as well as over a hundred printable resources  from across the A-level over on psych boost .com 

I do want to thank all the students and  teachers who have supported psych boost  

over on patreon during the development  of the research methods unit. It's their  

support that allows me to teach part time so I  can make psych boost on youtube for everyone. 

So thanks to them, and I will see you  all in the next research methods video, 

experimental design.