Chapter 2

Question 1

What is a population?

Answer 1

A complete group of items for which information is required

Question 2

What is consensus ?

Answer 2

The process of fully surveying a population

Question 3

What is a sample ?

Answer 3

A subset of the population

Question 4

How do we collect data ?

Answer 4

By statistical inference = reliable conclusions can only be made from samples that are representative of the population

Question 5

What is representative sample ??

Answer 5

A sample that is similar to the population on all characteristics, except that it includes fewer people

Question 6

What is a sampling frame ?

Answer 6

A complete list of potential items from which we draw items to be included in the sample

Question 7

What are probability samples ?

Answer 7

When each element of the population has a known probability of being included in the sample

Question 8

What is simple random sampling ?

Answer 8

Simple random sampling is obtained is each element in the population, not already in the sample, has an equal chance of being taken up into the sample on the next draw

Question 9

What is the method of simple random sampling ?

Answer 9

• List of all population elements, numbered
• Use a mechanical method to select the sample elements
• Use the table of random numbers (Table AI)
• Make use of the computer (random number generator)

Question 10

What is stratified sampling ?

Answer 10

When the population is divided into a number of natural, non-overlapping groups/strategy that are more or less homogenous

• elements are randomly selected from each group
• the number from each stratum is proportional to the population
• number of sample elective from each group may be different
• If this number of elements is proportional to the stratum size, the sample is called a proportionally stratified sample

Question 11

What is the stratified sampling method?

Answer 11

• 1st divide your population into males and females if you are using gender as your stratification variable
• Take a random samples from each group
• put those two sets together and you now have your final sample
• obtaining a sample with no or very few males/females is possible

Question 12

What is cluster sampling ?

Answer 12

When the population elements are naturally grouped together yo form so-called clusters where each cluster consists of a group of heterogenous elements

Question 13

What is the method of cluster sampling ?

Answer 13

• A number if clusters is randomly chosen
• All the elements from the chosen clusters are incorporated in the sample (one-stage cluster sampling)

OR

elements are randomly selected from the chosen clusters to be included in the sample (two-stage cluster sampling)

Question 14

What are the samples under Non-probability samples ?

Answer 14

• convenience sample
• judgement sample
• Quota sample

Question 15

What is a convenience sample ?

Answer 15

When a sample which is convenient for the researcher is taken and does not necessarily represent a population

• units are selected which are easily attainable and readily available

Question 16

What are judgement samples?

Answer 16

When samples are taken to include the “best” sample elements in the sample according to the researchers judgement

Question 17

What is a Quota sample ?

Answer 17

The non-probability equivalent of stratified sampling

• the population is divided into segments and a Quota element from each segment is included in the sample
• Quotas are sometimes based on proportions of populations, but the choice of sample elements is made according to a non-probability method (convenience or judgement)

Question 18

What do we have under errors and bias in sampling ?

Answer 18

• sample error
• sampling bias
• sampling observation errors

Question 19

What is sample error ?

Answer 19

A reflection of the inherent inability of the sample to provide completely accurate information about a population

• it is inherent to an sample, it cannot be avoided
• can bring decreased by taking a larger sample

Question 20

What is sampling bias ?

Answer 20

Sampling bias occurs when certain sections of the population are represented to a lesser degree or not represented at all

Question 21

What ade sampling observation errors ?

Answer 21

Errors incurred during the collection of data

• faulty or inaccurate measuring instruments, unreliability of the surveyor or respondent

Question 22

What are the responsibilities under errors and bias in sampling ?

Answer 22

• honesty when working with data
• anonymity vs confidentiality
• ethics are important when working with people
• Non-probability sampling methods are subjective