Sampling

Question 1

(Target) population

Answer 1

-a group of people that the researcher is interested in

└from which a smaller sample is drawn

Question 2

Sample

Answer 2

-a group of people who take part in a research investigation
└a sample is drawn from a target population
└and is presumed to be representative of that population

Question 3

Sampling techniques

Answer 3

-the method used to select people from the population

Question 4

Bias in sampling

Answer 4

• when certain groups are over or under represented in a sample
• limits the extent to which generalisations can be made to the target population

Question 5

Generalisation (sampling)

Answer 5

• the extent to which findings from an investigation can be applied to the population
• can generalise if the sample of participants is representative of the population

Question 6

Types of sampling

List

Answer 6

Volunteer sample
Random sample
Opportunity sample
Systematic sample
Stratified sample

Question 7

Random sample

Answer 7

-a sample where all members of the target population have an equal chance of being selected

Question 8

Random sample

Process

Answer 8

-list of all members of target population is obtained
-names on list assigned a number
-sample is generated through lottery method
└picking numbers from a hat, computer based randomiser

Question 9

Random sample

Evaluation

Answer 9

Strengths
-avoids researcher bias
└researcher has no influence over who is selected

Limitations

• difficult and time consuming (obtaining list of target population)
• sample may still not be representative
• selected participants may refuse to take part

Question 10

Systematic sample

Answer 10

-every nth member of the target population is selected

Question 11

Systematic sample

Process

Answer 11

-sampling frame is produced
└list of people from target population organised (e.g. into alphabetical order)
-sampling system is decided (nth person)
└may be randomly determined to reduce bias
-researcher works through sampling frame until the sample is complete

Question 12

Systematic sample

Evaluation

Answer 12

Strengths
-avoids researcher bias
└researcher has no influence over who is selected
-sample fairly representative

Limitations
-selected participants may refuse to take part

Question 13

Stratified sample

Answer 13

-a sample where the composition of the sample reflects the proportions of people in certain sub-groups (strata) within the target population

Question 14

Stratified sample

Process

Answer 14

-researcher identifies different strata in population
└representative proportions are worked out
-participants to make up each stratum are selected using random sampling

Question 15

Stratified sample

Evaluation

Answer 15

Strengths 
-avoids researcher bias
└researcher has no influence over who is selected 
-representative sample
└=can generalise to target population 

Limitations

• difficult and time consuming (obtaining list of target population)
• sample may still not be completely representative
• selected participants may refuse to take part

Question 16

Opportunity sample

Answer 16

-researchers select anyone who is willing and available

Question 17

Opportunity sample

Process

Answer 17

-researcher asks whoever is around at the time of their study

Question 18

Opportunity sample

Evaluation

Answer 18

Strengths
-convenient, less time and money

Limitations
-researcher bias
└researcher has complete influence over who is selected
-unrepresentative of target population as sample is taken only from one place
└can’t generalise

Question 19

Volunteer sample

Answer 19

-participants select themselves to be part of the sample (self-selection)

Question 20

Volunteer sample

Process

Answer 20

-e.g. researcher may place an advert in a news paper

Question 21

Volunteer sample

Evaluation

Answer 21

Strengths
-convenient, less time and money

Limitations
-volunteer bias- attracts certain type of person
└can’t generalise