Data Collection Flashcards
Advantages and disadvantages of using census for data collection
Measures/observes every member of a population
+ Results should be completely accurate
- Time consuming and expensive
- Hard to process large amounts of data
- Cannot be used when testing destroys process
Advantages and disadvantages of using samples for data collection
Measures/observes a subset of the population
+ Less time consuming and cheaper
+ Less data needs to be processed
+ Requires less people
- May be inaccurate, as whole population may not be represented
- Sample size may not be large enough to include all subsets of population
Types of sampling
Random and Non- random sampling
Random sampling methods
Simple random, systematic, stratified
Simple random sampling
Involves a sampling frame, where each member is numbered and then to acquire the samples, the number of samples required are used to randomly select members.
Can be done using calculator, random number generators or lottery sampling.
Simple random sampling advantages and disadvantages
+ Free of bias
+ Quick and easy to obtain results
+ Each sampling unit has a known equal chance of selection
- Not suitable for large samples and populations
- Sampling drama required
Systematic sampling
Required members are chosen at regular intervals from a list
Systematic sampling advantages and disadvantages
+ Simple and quick to use
+ Can be used for large samples and populations
- Could be bias if list is not randomly ordered
- Sampling frame required
Stratified sampling
Population is divided into mutually exclusive subsets, and a random sample is taken from each
How many from each subset= (number in each subset/ total population) x sample sized required
Stratified sampling advantages and disadvantages
+ Sample accurately reflects population structure
+ Each subset is taken into account
- Population must be clearly classified into strata (distinct subsets)
Non random sampling methods
Quota, oppurtunity
Quota sampling
Interviewer/ researcher selects a sample that reflects the characteristics of the whole population
Quota sampling advantages and disadvantages
+ Allows a small sample which can be representative of the whole population
+ No sampling frame required
+ Quick,cheap,easy
- Non- random sampling can introduce bias
- Population must be divided into groups, which may result in inaccuracies
Opportunity sampling
Uses participants that are able and willing, and who fit the criteria of the study
Opportunity sampling advantages and disadvantages
+ Easy and cheap
- Unlikely to provide result representative of whole population