Sampling and data collection techniques Flashcards
Define ‘cluster sampling’
Used when the data naturally splits into groups. The list of clusters is the sampling frame, and some clusters are randomly selected from it to make the sample.
Define ‘quota sampling’
Group the population by characteristics such as age/gender and interview a number from each group
Define ‘systematic sampling’
Choose a starting point from the sampling frame at random, and then choose items at regular intervals
Define ‘random sampling’
Every member of the population has an equal chance of being selected, which means this sampling method is unbiased and better represents the population
What are the advantages and disadvantages of random sampling?
Advantages:
> Sample is more likely to be representative of the population, provided it is large
> The members of sample are unbiased
Disadvantages:
> Needs a full list of the whole population
> Needs a large sample size
What are the advantages and disadvantages of cluster sampling?
When considering advantages and disadvantages:
> Whether the sample will be biased
> Whether the sample size will be sensible
> How quick and easy the method is
> How expensive it is to carry out
What are the advantages and disadvantages of quota sampling?
When considering advantages and disadvantages:
> Whether the sample will be biased
> Whether the sample size will be sensible
> How quick and easy the method is
> How expensive it is to carry out
What are the advantages and disadvantages of systematic sampling?
When considering advantages and disadvantages:
> Whether the sample will be biased
> Whether the sample size will be sensible
> How quick and easy the method is
> How expensive it is to carry out
What is the calculation for working out stratified sample size?
(no. in strata / total population) x required total sample size
Define ‘secondary data’
Data collected from a reference source, not collected yourself
Define ‘primary data’
Data collected by yourself through surveys or direct observation
What are the advantages and disadvantages of primary data?
Advantages:
> Unbiased and reliable as it is gathered first hand
> You have control over what data you are collecting, and who from
Disadvantages:
> Expensive to run, e.g: travel cost, creating/handing out surveys
> Limited to time, place and people available
What are the advantages and disadvantages of secondary data?
Advantages
> Someone has alreaday collected the data, which means it is quicker annd cheaper
> Can use a wider range of data as it could come from all over the world, and at almost any time
Disadvantages:
> Could be biased and is unreliable as someone else collected it, who could have edited the results, and you don’t know how it was collected
> Could be not the wanted data - unhelpful
What are the advantages and disadvantages of interviews?
Advantages:
> Interviewer can explain the question
> Interviewer can put people at ease when answering personal questions
> Respondent can explain answers
> High response rate - every person interviewed answers the questions
Disadvantages:
> Respondents may be less honest, and less likely to answer personal questions
> Interviewing can take a long time, so it can be expensive
> The sample size is smaller than for a questionnaire
> Interviewer may be biased - they may interpret the answers to suit their opinion
> Respondents may try to impress the interviewer, or guess the answer they think the interviewer wants to hear
What are the advantages and disadvantages of questionnaires?
Advantages:
> Respondents are more likely to respond honestly, and to answer personal questions
> Respondents can all complete the questionnaire at the same time, or in their own time, so it is quicker and cheaper
> Easy to send questionnaires to a large representative sample
> No biased interviewer
Disadvantages:
> Respondent may not understand the question
> Researcher may not understand the answer
> Lower response rate - some people may not return the questionnaire, or answer all the questions
