Sampling

Starter Complete the ethics key terms card sort in pairs

Learning Objectives: 1) To develop an understanding of sampling in psychology. Success Criteria: 1) Complete page 26 of your booklet with notes on types of sampling. 2) Play the True/False game to assess what you have learned today.

Sampling General population General population Target population      General population General population   Target population Target population  Sample Sample     

Sampling Researchers aim to get a sample that is representative of the target population Every type of person in the target population should be proportionally represented in the sample NB: it is not necessary for the sample to be representative of the general population unless the researcher intends to generalise

The population is the group of people from whom the sample is drawn The population is the group of people from whom the sample is drawn. For example if the sample of participants is taken from sixth form in Leicester, the findings of the study can only be applied to that group of people and not all sixth form students in the UK and certainly not all people in the world.

Obviously it is not usually possible to test everyone in the target population so therefore psychologists use sampling techniques to choose people who are representative (typical) of the population as a whole. = If your sample is representative then you can generalise the results of your study to the wider population.

Opportunity Sampling Common Room Geek! Want to be in my study? Common Room Opportunity sampling is the sampling technique most used by psychology students. It consists of taking the sample from people who are available at the time the study is carried out and fit the criteria you are looking for.

Random Sampling This is a sampling technique which is defined as a sample in which every member of the population has an equal chance of being chosen. This involves identifying everyone in the target population and then selecting the number of participants you need in a way that gives everyone in the population an equal chance of being picked.

Volunteer Sampling Psych Lab Volunteers needed for psychological study on learning I just love to be helpful…. I’ve always wanted to be in a study…. Sounds rubbish… Gotta do my hair.. Psych Lab Volunteer sampling (or self-selected sampling) consists of participants becoming part of a study because they volunteer when asked or in response to an advert.

Stratified Sampling = 60% female 40% male = 60% female 40% male Stratified sampling involves classifying the population into categories and then choosing a sample which consists of participants from each category in the same proportions as they are in the population.

Sampling random random quota quota How difficult to obtain opportunity volunteer volunteer How likely to be representative

Task Complete the table on page 26 of your booklet. Complete the questions on page 109 of the textbook.

Evaluation of sampling techniques Advantages Disadvantages Opportunity This is the easiest method as it is just the first participants that you find. This means that it takes less time to find a sample. It is biased as you draw the sample from only a small part of the target population (low population validity). Volunteer Access to a wide variety of participants which makes the sample less biased and more representative. Sample could be biased as people are more highly motivated to take part. Random The sample could be unbiased as all of the population have an equal chance of selection. The researcher could get a biased sample (e.g. more boys or girls) because the sample is too small.

True/False Game True/False Train A number of statements will appear on screen, as a class you need to identify whether the answer is true or false… Can you beat my other classes and get the longest train of correct answer?!! True/False Train

True or False? A sample is a part of the whole group of people being studied

True or False? A random sample is one where anybody who is available at the time are asked at random to be in the study

True or False? A volunteer sample will always be biased because volunteers are likely to be very interested in the topic being studied and/or have a specific personality type (the volunteering type) that make them atypical of people in general

True or False? Opportunity samples are often used in psychological research because they are cost and time effective and because other sample types are difficult to obtain

True or False? A strength of a random sample is that it is assumed that chance selection will cancel out biases and provide a sample representative of the target population

True or False? “The target population” is the same as “people in general”

True or False? Student samples are ideal for psychological research, especially when psychology students are used, as they take the study seriously and are convenient for researchers based in universities