Data collection

Question 1

What is a population?

Answer 1

All of the organisms that are of interest.

Question 2

What are sampling units?

Answer 2

Individual units of the population.

Question 3

What is a sampling frame?

Answer 3

A list of individually numbered members of a population.

Question 4

What is a census?

Answer 4

An investigation that observes every member of the population.

Question 5

What are the advantages of using a census?

Answer 5

1. The results should be completely accurate as you take into account all the data.

Question 6

What are the disadvantages of using a census?

Answer 6

1. It is relatively time-consuming and expensive.
2. There is a lot of data to process.
3. It can’t be used if the testing method causes damage to the sampling units.

Question 7

What is a sample?

Answer 7

An investigation into a small subset of the population which is used to find out information about the whole population.

Question 8

What are the advantages of using a sample?

Answer 8

1. It is less expensive and time-consuming.
2. Less data needs to be processed.

Question 9

What are the disadvantages of using a sample?

Answer 9

1. The results may not be accurate.
2. The sample may not be large enough to tell us anything about the small sub-groups of the population.

Question 10

What is simple random sampling?

Answer 10

Each sample of size n has an equal chance of being chosen.

Question 11

What are the advantages of simple-random sampling?

Answer 11

1. It is less time-consuming and expensive.
2. It is free of bias.

Question 12

What are the disadvantages of simple-random sampling?

Answer 12

1. A sampling frame is needed.
2. It is not suitable for larger populations.

Question 13

What is systematic sampling?

Answer 13

The sapling units are picked at regular intervals.

Question 14

What are the advantages of systematic sampling?

Answer 14

1. It is less time-consuming and inexpensive.
2. It is suitable for larger populations.

Question 15

What are the disadvantages of systematic sampling?

Answer 15

1. A sampling frame is needed.
2. Bias may be introduced if the sampling frame is not random.

Question 16

What is stratified sampling?

Answer 16

The population is separated into mutually exclusive strata and random samples are taken from each.

Question 17

What are the advantages of stratified sampling?

Answer 17

1. The sample accurately represents the population structure.
2. There will be proportional representation of groups within a population.

Question 18

What are the disadvantages of stratified sampling?

Answer 18

1. A sampling frame is needed when taking random samples from the strata.
2. It is time-consuming to separate the populations into groups.

Question 19

What is quota sampling?

Answer 19

A researcher chooses a sample that represents the characteristics of the population.

Question 20

What are the advantages of quota sampling?

Answer 20

1. A sampling frame is not needed.
2. Quick and inexpensive.
3. It allows a small sample to be representative of the population.

Question 21

What are the disadvantages of quota sampling?

Answer 21

1. Bias may be introduced as the sampling is not random.
2. Non-responses are not recorded.

Question 22

What is opportunity sampling?

Answer 22

The sample is made up of people who were available at the time of the experiment and met the criteria needed.

Question 23

What are the advantages of opportunity sampling?

Answer 23

1. Simple
2. Quick
3. Inexpensive

Question 24

What are the disadvantages of opportunity sampling?

Answer 24

1. The sample won’t be representative.
2. Highly dependent on the researcher.