Sampling Techniques

Question 1

What is the difference between a population and a sample?

Answer 1

• target pop is group of ppl who are the focus of researchers interest
• its not possible to include all members of target pop in research so researcher creates a sample which is representative of target pop by taking group of ppl from target pop to take part in research

Question 2

What are the five different sampling techniques?

Answer 2

Random sample
Systematic sample
Stratified sample
Opportunity sample
Volunteer sample

Question 3

What is random sampling, how is it conducted and what is a strength and weakness?

Answer 3

Every person in target pop has equal chance of being selected
- create a complete list of all target pop
- write names on equal sized pieces of paper and put in hat
- without looking, select number you want in sample from hat
Strength
- potentially unbiased
Weakness
- very time consuming

Question 4

Describe the strength potentially unbiased and weakness of very time consuming for a random sample

Answer 4

• potentially unbiased as everyone in tp has equal chance of being selected for study, so any extraneous variables will be equally divided bw the diff groups, inc int val
• very time consuming as it takes time collecting all names of ppts to take part in study + no guarantee ppts wanna take part in research

Question 5

What is a systematic sample, how is it conducted and what is a strength and weakness?

Answer 5

A system is applied to select ppts
- create sampling frame to organise target pop e.g. put in alphabetical order
- decide on system e.g. very 5th person is chosen until sample is made up
Strength
- avoids researcher bias
Weakness
- time consuming

Question 6

Describe the strength avoids researcher bias and weakness that its time consuming for systematic sampling

Answer 6

• avoids researcher bias as researcher has no influence over who is chosen to take part in study as it is obj once system to select ppts is est
• time consuming and difficult creating system and collecting names

Question 7

What is stratified sampling, how is it conducted and what is a strength and weakness?

Answer 7

Advanced way of sampling where makeup of sample reflects proportions of certain subgroups in tp
(E.g. if 70% of tp is female then sample will be 70% female)
- identify the different subgroups that make up a population e.g. males/females
- calculate how many of each proportion u would need for sample size
- use random sampling to gather number of ppts to make up proportion
Strength
- most representative sample
Weakness - very time consuming

Question 8

Describe the strength most representative sample and weakness very time consuming for stratified sampling

Answer 8

• most representative sample as it accurately reflects makeup of tp in correct proportions so findings can be gen to tp
• very time consuming as it takes time working out proportions of ppts needed + not guaranteed ppts wanna take part

Question 9

What are the two equations for stratified sampling?

Answer 9

If percentage is provided: (sample size wanted/100) x % size of sub group
If percentage isnt provided: (sample size wanted/target pop size) x sub group size

Question 10

What is meant by an opportunity sample, how is it conducted and what are the strengths and weaknesses?

Answer 10

Sample gained from ppts who are there in that moment of time
- go somewhere you will have access to pop you want to study and ask first 30 ppts who are there in that moment of time if they want to take part
Strength
- quick, easy and cheap
Weakness
- may not be representative of tp

Question 11

Describe the strength very quick, easy and cheap and weakness that it may not be representative of tp for opportunity sample

Answer 11

• very quick, easy and cheap as ppts chosen are available at time for your sample
• may not be representative of tp as those picked are present at same time, doing similar things so they might have similar personalities so difficult to gen findings to wider pop

Question 12

What is a volunteer sample, how is it conducted and what are the strengths and weaknesses?

Answer 12

Self selected method where ppl volunteer to take part in study
- place advert where ppl in tp will see it
- wait for first 30 ppl to reply
Strength
- easy and cheap
- sample may not be representative

Question 13

Describe the strength easy and cheap and weakness sample may not be representative for volunteer sample

Answer 13

• easy and cheap as all is required for study is an advert in place tp will be and to wait for ppt to volunteer
• sample may not be representative as only certain type of personality such as extroverts will volunteer so difficult to gen to tp