Data Collection Flashcards
Census
Observes or measure every member of a population
Sample
Selection of observations taken from subset of the population which is used to find out information about the population as a whole
Advantage of census
Gives a completely accurate result
Disadvantages of a census
Time consuming + expensive
Can’t be used when the testing process destroys the item
Hard to process large quantity of data
Advantages of Sample
Less time consuming + expensive than census
Fewer people have to respond
Less data to process than in a census
Disadvantages of Sampling
Data might not be accurate
Sample may not be large enough to give information about small sub-groups of the population
Simple random sample
Sample of size n is one where every sample of size n has an equal chance of being selected
Systematic sampling
The required elements are chosen at regular intervals from an ordered list
Stratified sampling
The population is divided into mutually exclusive strata and a sample is taken from each
Advantages of simple random sampling
Free of bias
Easy+cheap to implement for small populations+small samples
Each sampling unit has a known + equal chance of selection
Disadvantages of random sampling
Not suitable when population size or sample size is large as it is might be time consuming+ expensive
A sampling frame is needed
Systematic sampling advantages
Simple and quick to use
Suitable for large samples and large populations
Disadvantages of Systematic sampling
Sampling frame needed
Can be bias if sampling frame is not random
Stratified sampling advantages
Accurately reflects population structure
Guarantees proportional representation of groups within a population
Stratified sampling disadvantages
Population must be classified into distinct strata
Selection within each stratum suffers from the same disadvantages as simple random sampling
Quota sampling
An interviewer or researcher selects a sample that reflects the characteristics pf the whole population
Opportunity sampling
Consists of taking the sample from people who are available at the time of study is carried out + who fit the criteria you’re looking for
Advantages of Quota Sampling
Allows small sample to represent population
No sampling frame needed
Quick,easy + inexpensive
Allows easy comparison between different groups of a population
Disadvantages of quota sampling
Can introduce bias
Population must be divided into groups can be costly or inaccurate
Increasing scope of study increase number of study groups, adds time + expense
Non-responses aren’t recorded as such
Advantages of opportunity sampling
Easy to carry out
Inexpensive
Disadvantages of opportunity sampling
Unlikely to provide a representative sample
Very dependent on researcher
