www.curriculum-press.co.uk Number 49

SociologyFactsheet

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Sampling Techniques in Sociological Research

How do Sociologists decide who to study?

Before beginning research, the researchermust identify the target population – i.e. thegroup to be studied. This may be students,the unemployed, pensioners for example. Dueto the large number of people who fit intothese categories, it is not practically possibleto use every member of the target population.Therefore, it is necessary to select a small number of peoplefrom the target population – this is the sample.

In selecting the sample, a sampling frame, which is a complete listof all the members of the target population, is required. A samplingframe can be defined as the source from which the sample is drawn.Examples of a sampling frame would include the electoral registeror a school register. In some cases the sampling frame would needto include more detailed information e.g. ages, if this is appropriatefor the research.

Researchers are often interested in making generalisations aboutthe group they are studying. Generalisations are general statementsand conclusions that apply not only to the sample but to the targetpopulation as a whole. If the researcher is to generalise, then it isessential that the sample is representative (typical) of the targetpopulation.

Careful choice of sampling technique is a vital aspect of sociologicalresearch because poor choice of participants can invalidate anyconclusions drawn from the research.

This Factsheet will examine the different sampling methods availableand discuss their advantages and disadvantages.

Exam Hint You need to be able to explain the choice ofsampling method in any research you analyse and anyresearch you conduct. You will also be expected to explainwhy certain sampling techniques are appropriate for theresearch conducted.

Non Random Sampling

1. Systematic2. Snowball3. Quota4. Opportunity5. Volunteer

Random Sampling

1. Simple2. Stratified3. Cluster

There are a number of techniques used by sociologists in order toobtain a sample. These sampling techniques fall into two categories.

The size and type of sample will depend on a number of factors including:

If the research is to take a long time, some participants may not wishto continue or some may be ‘lost’ due to moving house etc.

Limited funding will limit the size of the study and consequently thesize of the sample

Just one researcher restricts the number of participants that can beeffectively studied

Questionnaires can be delivered to many more people than in-depthinterviews can in the same period.

If the researcher wishes to generalise the findings, a representativesample will be required

How long the research might take

How much funding the research has

How many researchers there are

The method used.

Whether the sociologist wishes to generalize

Sociology Factsheet49. Sampling Techniques in Sociological Researchwww.curriculum-press.co.uk

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Random SamplingA random sample is where each member of the sampling frame has an equal chance of being selected. If the sample is selectedrandomly, it is likely that it will mirror the target population, therefore conclusions can be made and generalisations can be drawn.

Sampling Technique

Simple random sample Every individualhas an equal chance of selection. Giveevery participant in the targetpopulation a number. Use acalculator, spreadsheet orrandom number tables to selectthe individuals in the sample orpull numbers out of a hat

Stratified random sampleThis involves dividing the targetpopulation into non-overlappingcategories called strata e.g by age orgender. This will depend on what issignificant for the investigation. A sampleis then drawn randomly from each subpopulation. You might therefore have ahat for males and one for females.

Cluster sampleThis is a type of sampling in which thetarget population is first divided intosmaller groups or clusters rather thanrandomly selected from the wholepopulation. Random samples are thendrawn from the clusters.Cluster sampling is usuallyused when both thepopulation and the desiredsample size are particularlylarge. A village, town or citymay be chosen to be representative of awider area.

Disadvantages

If the population is very heterogeneous the resultscan vary considerably. May be difficult to do forlarge/ dispersed populations.

Detailed information about the population isrequired to define the strata. It is crucial to choosethe correct stratification according to factors thataffect the investigation - this may need to berefined during the investigation.

Clusters may not be representative of the entirepopulation – important subgroups may be left out.Statistical analysis more complicated.

Advantages

Only practical for small samples.Simple method. Data analysissimple and has soundmathematical basis.

If the population is veryheterogeneous, it gives a morerealistic picture than simplerandom, and ensuresrepresentation of key strata.

Particularly useful for a verylarge or dispersed targetpopulation. Does not require acomplete list of all participantsin the target population - justfor the clusters chosen.

Coursework Hint: For coursework you will only be required to carry out a small scale study and a non random sampling technique willprobably be more appropriate. You will need to explain why you have used the technique, explaining the advantages and the disadvantages.When you evaluate your research you should discuss how your sample could have been more representative of the target population ifyou had used a random sampling technique.

Exam Hint:-You may be asked in the exam to define terms such as:what is meant by a “representative” sample Examiners would award two marks for an appropriate explanation or definition of arepresentative sample, such as a smaller cross section of the research population or a smaller part that has the same proportionatecharacteristics as the research population. Simple tautological responses such as ‘a representative sample is a sample representing…’will not be rewarded. More successful, responses achieving two marks by means of describing how a representative sample mightbe constructed or might take into account social characteristics such as age, gender, etc.

What is meant by a “sampling frame” Examiners would award two marks for an appropriate explanation or definition, such as: alist of all members of the research population. One mark would be awarded for an example only, such as: electoral roll. Responsessuggesting that a sampling frame is a list of members of a research sample will not be rewarded. Answers should be more accurateand detailed and should include an appropriate example to confirm understanding.

Sociology Factsheet49. Sampling Techniques in Sociological Researchwww.curriculum-press.co.uk

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Non Random SamplingWith a non random sampling method, some individuals in the sampling frame have no chance of being selected (eg if you obtained yoursample of 18 year old males solely from your college, those not attending it have no chance of being selected)

Non random methods cannot be relied upon to produce representative samples, and they can be susceptible to bias – either by the persondoing the sampling or by the people volunteering/allowing themselves to be sampled. However they are generally quicker and easier touse than random methods. They are suitable for pilot surveys and exploratory research.

Sampling technique

SystematicThis technique is frequently used when thesampling frame is in a list e.g. school registeror electoral roll. This involves applying asystem to the selection of participants e.g.taking every nth name from the sampling frame.Out of a group of 500 people 50 may be chosenby randomly selecting a number between 1and 10 e.g. 6, every 10th name from the samplingframe i.e. 6,16, 26,36 and so on is selected asthe sample

Snowball samplingA sociologist may be interestedin studying a population for whichthere is no sampling frame e.g.those who work for cash and do not declare it.

Without a sampling frame, the researcherwould not be able to select a random orsystematic sample. Using a snowball sample,the researcher would begin by making contactwith one member of the target population,gradually gaining their confidence until thatperson is willing to tell the name(s) of others

Quota samplingThis is where a researcher will select the acertain number of people from categories orgroups such as females, pensioners, in directproportion to their existence in the populationas a whole e.g. 60% the target population isfemale, so 60% the sample must also be female.People from each category can be selected byany easy method – such as opportunity orvolunteer sampling. Example : MarketResearch.

Opportunity SampleUses people from the target population whoare wiling and available at the time.

Volunteer sampleUses people from the targetpopulation who selectthemselves – e.g. by respondingto an advertisement. Researcher merely hasto check they are in the target population.

Disadvantages

Results may be biased (e.g. in a road withhouses in terraces, end-terrace houses -which are more expensive - will occur atperiodic intervals).

Unlikely to be representative. Difficult andtime consuming to collect a sample Mayraise ethical issues

Need to know a lot about the population tobe studied. Within quota the sampling maybe unrepresentative. Assessment of e.g.social class may be subjective.

Unlikely to be representative of the targetpopulation.

Self-selected participants are very unlikelyto be representative - in many cases theymay have a particular “agenda”.

Advantages

Easier to carry out than simple random,with less chance of mistakesParticularly useful with largepopulations. More evenly spread overpopulation than simple random.

Allows a study to be conducted withparticipants which would not normallybe conducted.

Sampling frame not needed.

Quick and easy to do. Sampling framenot needed.

All participants are willing to beinvolved. Sampling frame not needed.Quick and easy to do.

Sociology Factsheet49. Sampling Techniques in Sociological Researchwww.curriculum-press.co.uk

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Acknowledgements: This Sociology Factsheet was researched and written by Rosie Owens.Curriculum Press. Bank House, 105 King Street, Wellington, TF1 1NU. Sociology Factsheets may be copied free of charge by teaching staff or students, provided that their school is a registered subscriber. No part of these Factsheetsmay be reproduced, stored in a retrieval system, or transmitted, in any other form or by any other means, without the prior permission of the publisher. ISSN 1351-5136

Test your knowledge!

1. What is the difference between random and non random sampling?

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2. What is a target population?

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3. What is a sampling frame?

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4. Identify one random sampling technique and identify one advantage and one disadvantage of this sampling technique

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5. Identify one random sampling technique and identify one advantage and one disadvantage of this sampling technique

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Which sampling technique would you use in the following research?Give reasons for your choice.

1. You have been asked to research whether there are differences in the games that boys and girls engage in when they are in the schoolplayground area.

2. In recent years there has been a great emphasis on encouraging healthy eating in schools.You have been asked to investigate whether the students in your school have healthy eating habits

3. You have been asked to investigate the attitudes towards dieting in young people from different backgrounds.