Data Collection Flashcards
Advanatges of a census
It should give a completely accurate result
Advantages of a sample
- Less time consuming
- Less expensive
- Fewer people have to respond
- Less data to process
Diasdvanatges of a census
- Time consuming and expensive
- Cannot be used for destructive testing
- Hard to process large quantities of data
Disadvanatges of a sample
- The data may not be as accurate
- The sample may not be big enough to give data about small sub groups.
What is a population?
A whoile set of items that are of interest
What is a sample?
A selection of observations taken from a subset of the population which is used to find out information about the population as a whole
What is a census?
Observes or measures every member of a population
What is stratified sampling?
The population is divided into mutually exclusive strata and a random sample is taken from each
The proportion from each strata should be the same
Advantages of random sampling
- It removed bias from the sample
- It should be representative of the population
What is a sampling unit?
An induvidual unit of a population
Advantages of simple random sampling
- Free of bias
- Easy and cheap to implement for small populations
- Each sampling unit has a known and equal chance of being selected
What is simple random sampling?
Every sample has an equal chance of being selected.
You need a sampling frame where each person or thing is assigned a unique number, a selection of these numbers is then chosen at random
Numbers are either randomly generated or drawn through the lottery method.
Disadvantages of simple random sampling
- Not sutable when the population size is very large
- A sampling frame is needed
Advantages of systematic sampling
- Simple and quick to use
- Sutable for large samples and large populations
Advantages of stratified sampling
- Sample accurately reflects the population structure
- Guarantees proportional representation
Disadvantages of systematic sampling
- A sampling frame is needed
- It can introduce bias if the sampling frame is not random
Disadvantages of stratified sampling
- Population must be clearly clasified into distinct strata
- Selection within each stratum suffers from the same disadvantages as simple random sampling
Advantages of quota samping
- Allows a small sample to still be representative
- No sampling fram required
- Quick, easy and inexpensive
- Allows for easy comaprision between different groups within a population
Disadvantages of quota sampling
- Non random samping can introduce bias
- population must be divided into groups
- Increasing score increases the number of groups incresing time and expendse
- Non responses are not recorded as such
What is quota sampling?
An interviewer or resercher selects a sample that reflects the characteristics of the whole population
What is opportunity sampling?
A sample is taken from people who are availabe at the time the study is carried out and who fit the criteria you are looking for
Advantages of opportuinty sampling
- Easy to carry out
- Inexpensive
Disadvantages of opportunity sampling
- Unlikely to provide a representative sample
- Highly dependant on induvidual reasercher
