Populations and Samples Flashcards
What are the advantages of census data?
- It should give a completely accurate result
What are the disadvantages of census data?
- Time consuming and expensive
- Hard to process a large quantity of data
What are the advantages of sample data?
It- Less time consuming and expensive than a census
- Fewer people have to respond
- Fewer data to process than a census.
What are the disadvantages of sample data?
- The data may not be as accurate
- The sample may not be large enough to give information about small sub-groups of the population.
What are the individual units of a population known as?
- Sampling units
When sampling units of a population are individually named what are they called?
- Sampling frame
What are the three main ways of sampling data?
- Simple random sampling
- Systematic sampling
- Stratified sampling
What is simple random sampling?
- Where every size n has an equal chance of being selected.
How do you carry out simple random sampling?
- Allocate people a number
- Then generate the random number (lottery sampling)
What is systematic sampling?
- The required elements are chosen at regular intervals from an ordered list.
Give an example of systematic sampling
- If sample 20 was required from a population of 100, you would take every fifth person since 100 / 20 = 5.
What is stratified sampling?
-The population is divided into mutually exclusive strata( males and females ) and a random sample is taken from each.
What are the advantages of simple random sampling?
- Free of bias
- Easy and cheap to implement
- Each sampling unit has a known and equal chance of selection.
What are the disadvantages of simple random sampling?
- Not suitable when the population size or the sample size is large.
- A sampling frame is needed.
What are the advantages of systematic sampling?
- Simple and quick to use
- Suitable for large samples and large populations
What are the disadvantages of systematic sampling?
- A sampling frame is needed
- It can introduce bias if the sampling frame is not random
What are the advantages of stratified sampling?
- Sample accurately reflects the population structure
- Guarantees proportional representation of groups within a population.
What are the disadvantages of stratified sampling?
- Population must be clearly classified into distinct strata.
What are the two methods of non-random sampling?
- Quota sampling
- Opportunity sampling
What is another name for ‘Opportunity sampling’?
- convenience sampling
What are the advantages of Quota sampling?
- Allows a small sample to still be a representation of the population
- No sampling frame is required
- Quick, easy, and inexpensive.
What are the disadvantages of Quota sampling?
- Non-random sampling can introduce bias.
- Population must be divided into groups, which can be inaccurate.
What is opportunity sampling?
- Opportunity sampling consists of taking the sample from people who are available at the time the study is carried out and who fit the criteria you are looking for.
What is quota sampling?
- In quota sampling, an interviewer or researcher selects a sample that reflects the characteristics of the whole population.
