L6 - Sampling Techniques & Pilot Studies

Question 1

Target population

Answer 1

• group researchers are studying and want to generalise results to
  E.g. all females aged 20-30 who shop online
• sampling techniques are used to obtain sample of target population - can avoid studying whole population as would take too long and be too expensive

Question 2

Sample

Answer 2

Should be representative of population from which it’s drawn and should have the same characteristics as population
E.g. reflect social classes/ethnicities etc…

Question 3

Random sampling

Answer 3

• every member of target population has same chance of being selected
• place population names in had then select sample
  e.g. first 20 names chosen out of 100

Question 4

Advantages of random sampling

Answer 4

• if target population is large and large sample is chosen then it’s likely sample will be representing so results can be generalised from sample to target population
• no researcher bias when selecting sample, as it’s been chosen by chance without any conscious choice from researcher - equal chance of being chosen

Question 5

Disadvantages of random sampling

Answer 5

• can be difficult to get full details of a target population from which to select a sample
  E.g. getting women aged 20-30 may be hard as some not registered/in prison

Question 6

Systematic sampling

Answer 6

• Participants selected by taking every Nth person from a list
  E.g. make list of total population then choose every 6th person to be part of sample

Question 7

Systematic sampling advantages

Answer 7

• simpler then random sampling as it only needs a list of target population then the researcher chooses every nth person - random sampling needs more time/effort (writing names on slips etc..)

Question 8

Systematic sampling disadvantages

Answer 8

• selection process can interact with hidden periodic trait within population, if selection coincides with periodicity of trait then it would no longer be random
• not all members of target population who are selected will be available/willing to take part - could make sample unrepresentative, some may refuse to take part, reduces size dramatically

Question 9

Stratified sampling

Answer 9

• classifying population into categories and then randomly choosing sample consisting of participants from each category in same proportions as in population
• population divided into strata in terms of characteristics e.g. age, gender etc…

Question 10

Stratified sampling advantages

Answer 10

• all groups in population included so it should be representative of population

Question 11

Stratified sampling disadvantages

Answer 11

• Can be very time consuming as categories have to be identified/calculated, if you don’t have details of all people in target population/relevent strata it would be harder to conduct sample

Question 12

Opportunity sampling

Answer 12

• select participants who are readily available and willing to take part
• known as convenience sampling - select participants as it’s convient to do so
• may have easy access to a group of people they know well/have regular contact with

Question 13

Opportunity sampling advantages

Answer 13

• Easiest and most practical method
• especially compared to stratified sampling which may be expensive and time consuming

Question 14

Opportunity sampling disadvantages

Answer 14

• High chance it won’t be representative of target population
• sometimes people feel obligated to take part in research (esp. if they know person) even if they don’t want to - this is unethical

Question 15

Volunteer sampling

Answer 15

• people volunteer to participate in study - researcher usually advertises for people to take part through leaflets, posters, radio or TV broadcasts
• means people take notice of info and then can decide if they would like to take part in research and volunteer time

Question 16

Volunteer sampling advantages

Answer 16

• saves researcher time and effort
• just need to construct some type of advertisement and then wait out for the participants to come to them and volunteer time and involvement
• better then other methods where researcher needs to ask people to take part and ask for full commitment

Question 17

Volunteer sampling disadvantages

Answer 17

• a certain type of person tends to volunteer (enthusiastic, interested about topic) and this means there’s a high chance that sample obtained will be unrepresentative and won’t accurately represent target population - (volunteer bias)

Question 18

Pilot study

Answer 18

• A pilot study is an initial run-through of the procedures to be used in an investigation; it involves selecting a few people and trying out the study on them.
• It is possible to save time, and in some cases, money, by identifying any flaws in the procedures designed by the researcher.
• can help the researcher spot any ambiguities (i.e. unusual things) or confusion in the info given to participants or problems with the task devised.
• Sometimes the task is too hard, and the researcher may get a floor effect, because none of the participants can score at all or can complete the task - all performances are low.
• The opposite effect is a ceiling effect, when the task is so easy that all achieve virtually full marks or top performances and are “hitting the ceiling”.

Question 19

Pilot study - self-report

Answer 19

• When using self-report measures it is important to check as part of the pilot study:
  • The participants understand the questions and are prepared to answer them
  • That closed questions offer suitable options
  • Whether open questions are also needed to elicit unpredictable responses
  • Whether the reporting method is appropriate, e.g. if a face-to-face interview is too intimidating should it be changed to a questionnaire?

Question 20

Pilot study - observations

Answer 20

In observations it is important to check:
• Observers agree on operational definitions of behavioral categories
• Inter-observer reliability - do the researchers need practice observing the behaviours?
• The behavioural categories include all the important behaviours
• The behavioural categories do not overlap
• Whether the participants are affected by the observers - should they be covert?

Question 21

Pilot study disadvantage

Answer 21

• can be misleading due to small sample size, may not show problem that would be visible in a large sample size

Question 22

Pilot study advantage

Answer 22

• it can identify problems in the study beforehand, saving time and money