Sampling

1. Sampling

2. Sampling • Sociologist often aim to produce generalisations that apply to all cases of the topic they are interested in, • E.g. educational achievement – applies to all students regardless of class, gender or ethnicity. • Surveys are time consuming and it is impossible to conduct a survey where you would sample every single pupil studying in the UK.

3. Sampling • When conducting a piece of research it would be impossible to study the entire population. It costs too much and would be time consuming. • Instead researchers take a sample to the population that will be represent the views of the population – this is called a representative sample. • A sample can be considered not representative if it does not include a mixture of ages, gender and people from different areas.

4. Key Terms • Target population-is the entire group a researcher is interested in; the group about which the researcher wishes to draw conclusions. • Representative – if a sample is representative it represents the target population. • Generalisability – This means the findings can me used to make general assumptions about different groups.

5. Sampling frame • “A sampling frame is a list or other device used to define a researcher's population of interest. The sampling frame defines a set of elements from which a researcher can select a sample of the target population. Because a researcher rarely has direct access to the entire population of interest in social science research, a researcher must rely upon a sampling frame to represent all of the elements of the population of interest. • Generally, sampling frames can be divided into two types, list and nonlist. Examples of list frames include a list of registered voters in a town, residents listed in a local telephone directory, or a roster of students enrolled in a course”.

6. Random Sampling • Random sampling is based on the idea that if the sample is chosen at random then everyone has an equal chance of being selected, so you would get a better mix of people from your target population. • Random samples consist of selecting names from a list called a sampling frame. • The sampling frame needs to be representative of the group that the researcher wishes to study.

7. Strengths and limitations of Random Sampling • Reduces Bias • More likely to be representative • Increases possibility for generalisability. • If sampling frame is flawed then results will be flawed. • Researcher lack of control over choice of participants

8. Self-Selected Sampling • Can be called Volunteer sampling. • This is were individuals offer to be part of the sample. • It is easy to do and can reach a variety of participants.

9. Strengths and limitations of self- selected samples. • Quick and easy to get sample • Participants motivated to complete survey and answer honestly • Biased Results • Not representative • Lacks generalisability

10. Stratified Sampling • Stratified sampling involves classifying the population into groups and then choosing a sample which consists of participants from each group in the same proportion as they are in the target population. For example if we wanted to take a sample of students in the 6th form and 20% of all the 6th form have jobs then 20% of our sample should have jobs.

11. Strengths and Limitations of Stratified Sampling • Representative of target population. • Can be generalised. • Time consuming • Need details of your target population to replicate in your sample

12. Snowball Sampling • Snowball sampling is a non- probability sampling technique. • Existing participants in sample get their friends and family to join in with the sample. • Therefore it has a snowball effect – starts small and gets bigger. • As the sample gets bigger more data is collected. • Often used were access to the target population is difficult.

13. Strengths and limitations of snowball sampling • Easier to get sample- only recruit a small amount then it grows from that. • Useful in hidden populations as you only need access to a few people to begin with. • Bias • Not representative • Not generalisable • Very respondent driven

14. Quota Sampling • This is where the researcher goes and selects participants according to their research. • The choice is completely up to the researcher and may produce unreliable or invalid results.

15. Systematic Sampling Sampling frame (e.g. my register) 2 1 3 2 1 1 3 Number the participants in your sampling frame (e.g. 1,2,3) and then pick participants at a set interval (gap), e.g. every ‘number 1’ participant

16. Non representative sampling • As we have seen in the previous slides, sampling is important in ensuring that the people we include in our study are representative of the research population. • However, forte both practical and theoretical reasons, not all studies will use representative sampling techniques.

17. What do you think ? • What practical reasons do you think might affect the possibility of a researcher achieving a representative sampling ?

18. Practical reasons • Social characteristics of the research population, such as gender, age and class may not be known. It would be impossible to create a sample that was an exact cross section of the research population. • It may be impossible to find or create a sampling frame for that particular research – crime. • Potential participants may refuse to participate in the survey.

19. Practical reasons continued … • In cases where sociologist might not be able to obtain a representative sample, they will use a snowball or opportunity sample. • SS - Not representative, but a useful way to contact a sample of people who might otherwise be difficult to find such as criminals, • OS – also known as convenience sampling which involves choosing people who are easier to access – passers by. Again, this sample is less likely to be representative of the target research population.

20. What do you think ? • How might the interprevists and positivists approach sampling ?

21. Theoretical reasons • Interprevists believe it is more important to gain valid data and an authentic understanding of social actors than to discover general laws of behaviour. • Therefore, they are less concerned making generalisations, thus have less need for representative sample.

22. 5 – 5 – 1 Summarise today’s topic in 5 sentences. Reduce to 5 words. Now to 1 word.