Population + Sampling

Question 1

Population

Answer 1

The group of people who are the focus of the researcher’s interest, from which a smaller sample is drawn
* e.g. students attending colleges in London

Question 2

Opportunity sample

Answer 2

Simply selecting anyone who happens to be willing and available (ask whoever is around at the time of their study)

Question 3

Random Sample

Answer 3

• All members of the population have a equal chance of being selected
• 1st - obtain a complete list of all members of the target
• 2nd - all names on the list are assigned a number
• Actual sample - selected through use of some lottery method (computer/phone randomisers/hat picking)

Question 4

Systematic Sample

Answer 4

• When every nth member of the target population is selected - e.g. every 3rd house
• Sampling frame - list of people in target organised - e.g. alphabetical order
• Sampling system nominated - e.g. every 3rd, 6th or 8th person
• May begin from a randomly determined start to reduce bias.
• Researcher works through sampling frame until its complete

Question 5

Stratified Sample

Answer 5

• composition of the sample reflects the proportions of people in certian subgroups (strata) within the target population/wider pop
• 1st - identifies the different strata that make up the pop
• 2nd - calculate the required proportion for the sample to be representative
• 3rd - pps that make up each stratum are selected using random sampling

Question 6

Example: Stratified

Answer 6

Manchester (football)
* 40% support Man United
* 40% support man city
* 15% for Bolton
* 5% for Leeds
Stratified sampling of 20 pps - 8 (united), 8 (city), 3 (bolton), 1 (Leeds)
* Each of these would be randomly selected from larger grp of fans of their team

Question 7

Volunteer Sample

Answer 7

Involves pps selecting themselves to be part of the sample; self-selection
* get pps using adverts in newspaper, notice board
* Or when asked by researcher pps may simply raise hand

Question 8

EVAL: Random (strength)

Answer 8

Potentially unbiased - confounding/extraneous v should be equally divided between the diff grps, enhancing internal validity

Question 9

EVAL: Random (weakness)

Answer 9

1. Difficult + timeconsuming - complete list of target population hard to obtain
   * may still end up with unrepresentative sample
2. selected pps may refuse to take part - unrepresentative sample/looks like volunteer

Question 10

EVAL: Systematic (Strength)

Answer 10

• Objective - once system for selection established the researcher has no influence over who is chosen

Question 11

EVAL: Systematic (Weakness)

Answer 11

• Time consuming
• pps refuse to take part

Question 12

EVAL: Stratified (Strength)

Answer 12

Representative - designed to accurately reflect the composition of the pop = generalisation of findings becomes possible

Question 13

EVAL: Stratified (weakness)

Answer 13

Stratification not perfect - identified strata cannot reflect all the ways that people are different - complete representation of target pop not possible

Question 14

EVAL: Opportunity (S)

Answer 14

• Convenient - less costly in time +money than random - list of members not required
• no need to divide pop into diff strata like in stratified

Question 15

EVAL: Opportunity (W)

Answer 15

* Unrepresentative of target pop - drawn from specific area
* Researcher has complete control over the selection of participants + avoid (researcher bias)

Question 16

EVAL: Volunteer (S)

Answer 16

• Easy - minimal input + time consuming
• Ends up with pps who may be more engaging

Question 17

EVAL: Volunteer (W)

Answer 17

Volunteer bias - may attract a certain ‘profile’ of person (more curious + more likely to please the researcher) - affects extent of findings generalisability