1- Data Collection Flashcards
(17 cards)
What is simple random sampling and how is it used?
Method of sampling where all sampling units have an equal chance of being selected, it is used by giving every unit an identifying number and using a random number generator.
What are the advantages and disadvantages of simple random sampling?
Advantages- Bias free, easy, cheap.
Disadvantages- Unsuitable for large population size, sampling frame needed
What is systematic sampling?
Required elements are chosen in regular intervals in an ordered list.
How is systematic sampling carried out?
Take every kth term where k=population size/sample size starting at a random item between 1 and k.
What are the advantages and disadvantages of systematic sampling?
Advantages- Simple and quick, suitable for large population
Disadvantages- Sampling frame needed, can introduce bias
What is stratified sampling?
Population is divided into strata and simple random sampling is carried out in each strata. This method is used for a large sample already set in groups.
How is stratified sampling carried out?
Number sampled in each stratum=(strata size/population size) x overall sample size
What are the advantages and disadvantages of stratified sampling?
Advantages- Reflects population structure, guarantees proportional representation between groups.
Disadvantages- Population must be clearly classified into distinct data, selection within stratum has the same disadvantages as simple random sampling.
What is quota sampling and how is it carried out?
Population is divided into groups according to a characteristic. A quota of units in each group is set.
An interviewer selects sampling units
What are the advantages and disadvantages of quota sampling?
Advantages- Quick and easy, allows small sample to be representative of entire population
Disadvantages- Dividing into groups could be costly or inaccurate, non responses aren’t recorded
What is opportunity sampling?
Sample taken from people who are available at time of study and meet criteria e.g: people carrying shopping bags outside a supermarket for a survey on shopping habits.
What are the advantages and disadvantages of opportunity sampling?
Advantages- Easy and cheap
Disadvantages- Unlikely to provide representative sample, highly dependent on researcher
List all random and non-random sampling types.
Random- Simple random sampling, systematic sampling, stratified sampling.
Non-random- Quota sampling, opportunity sampling.
What is discrete data?
Discrete data is data that is counted, not measured, and can’t be divided into smaller parts.
What is continuous data?
Data that is measured not counted, and has an infinite number of possible values.
List all the weather stations involved in the large data set, listed from north to south.
Leuchars, Leeming, Heathrow, Hurn, Camborne, Beijing, Jacksonville, Perth.
What is trace/tr?
Trace means between 0 and 0.05mm of rainfall. In calculations, treat these as 0.
