Data collection Flashcards
What is a population?
All of the organisms that are of interest.
What are sampling units?
Individual units of the population.
What is a sampling frame?
A list of individually numbered members of a population.
What is a census?
An investigation that observes every member of the population.
What are the advantages of using a census?
- The results should be completely accurate as you take into account all the data.
What are the disadvantages of using a census?
- It is relatively time-consuming and expensive.
- There is a lot of data to process.
- It can’t be used if the testing method causes damage to the sampling units.
What is a sample?
An investigation into a small subset of the population which is used to find out information about the whole population.
What are the advantages of using a sample?
- It is less expensive and time-consuming.
- Less data needs to be processed.
What are the disadvantages of using a sample?
- The results may not be accurate.
- The sample may not be large enough to tell us anything about the small sub-groups of the population.
What is simple random sampling?
Each sample of size n has an equal chance of being chosen.
What are the advantages of simple-random sampling?
- It is less time-consuming and expensive.
- It is free of bias.
What are the disadvantages of simple-random sampling?
- A sampling frame is needed.
- It is not suitable for larger populations.
What is systematic sampling?
The sapling units are picked at regular intervals.
What are the advantages of systematic sampling?
- It is less time-consuming and inexpensive.
- It is suitable for larger populations.
What are the disadvantages of systematic sampling?
- A sampling frame is needed.
- Bias may be introduced if the sampling frame is not random.
What is stratified sampling?
The population is separated into mutually exclusive strata and random samples are taken from each.
What are the advantages of stratified sampling?
- The sample accurately represents the population structure.
- There will be proportional representation of groups within a population.
What are the disadvantages of stratified sampling?
- A sampling frame is needed when taking random samples from the strata.
- It is time-consuming to separate the populations into groups.
What is quota sampling?
A researcher chooses a sample that represents the characteristics of the population.
What are the advantages of quota sampling?
- A sampling frame is not needed.
- Quick and inexpensive.
- It allows a small sample to be representative of the population.
What are the disadvantages of quota sampling?
- Bias may be introduced as the sampling is not random.
- Non-responses are not recorded.
What is opportunity sampling?
The sample is made up of people who were available at the time of the experiment and met the criteria needed.
What are the advantages of opportunity sampling?
- Simple
- Quick
- Inexpensive
What are the disadvantages of opportunity sampling?
- The sample won’t be representative.
- Highly dependent on the researcher.
