chapter 1 - data collection

Question 1

census

Answer 1

observes or measures every member of the population

Question 2

sample

Answer 2

selection of observations taken from a subset of the population which Is used to find out information about the population as a whole

Question 3

advantages of a census

Answer 3

gives a completely accurate result

Question 4

disadvantages of a census

Answer 4

• time consuming
  -expensive
  -cannot be used when testing destroys the item
  -hard to process large quantity of data

Question 5

advantages of a sample

Answer 5

• less time consuming and expensive than a census
• fewer people have to respond
• less data to process than a census

Question 6

disadvantages of a sample

Answer 6

• data may not be accurate
  -sample may not be large enough to give information about small subgroups of the population

Question 7

simple random sample

Answer 7

every member of the population has an equal chance of being selected

Question 8

advantages of simple random sampling

Answer 8

• free of bias
• easy and cheap to implement for small populations and small samples
  -each sampling unit has a known and equal chance of selection

Question 9

disadvantages of simple random sampling

Answer 9

-not suitable when the population size or sample size is large
-sampling frame is needed

Question 10

systematic sampling

Answer 10

required elements are chosen at regular intervals in an ordered list

Question 11

stratified sampling

Answer 11

population is divided into mutually exclusive strata (e.g males and females) and a random sample is taken from each

Question 12

stratified sampling formula

Answer 12

(number in each stratum/population size) x overall sample size

Question 13

advantages of systematic sampling

Answer 13

• simple and quick
  -suitable for large samples and large populations

Question 14

disadvantages of systematic sampling

Answer 14

• sampling frame is needed
  -introduce bias if the sampling frame is not random

Question 15

advantages of stratified sampling

Answer 15

-sample accurately reflects the population structure
- guarantees proportional representation of groups within a population

Question 16

disadvantages of stratified sampling

Answer 16

• population must be clearly classified into distinct strata
  -selection within each stratum suffers from the same disadvantages as simple random sampling

Question 17

quota sampling

Answer 17

interviewer or researcher selects a sample that reflects the characteristics of the whole population

Question 18

opportunity sampling

Answer 18

taking a sample of people who are available at the time the study is carried out and who fit the criteria you are looking for

Question 19

advantages of quota sampling

Answer 19

-allows a small sample to still be representative of the population
-no sampling frame required
-quick, easy and inexpensive
-allows for easy comparison between different groups within a population

Question 20

disadvantages of quota sampling

Answer 20

• non random sampling can introduce bias
  -population must be divided into groups, which can be costly or inaccurate
  -increasing scope of study increases number of groups, which adds time and expense
  -non-responses are not recorded as such

Question 21

advantages of opportunity sampling

Answer 21

-easy to carry out
-inexpensive

Question 22

disadvantages of opportunity sampling

Answer 22

-unlikely to provide a representative sample
-highly dependent on individual researcher