Sampling Flashcards
What is Simple Random Sampling?
Each sampling unit is numbered within the sampling frame. Using a random number generator, select the sampling units.
2 Advantages and Disadvantages of Simple Random Sampling
A = Bias free, easy and cheap
D = Not suitable for large populations, sampling frame needed.
What is Systematic Sampling?
Population size/sample size = k. Take a random number from 0-k and at regular intervals of k record the sampling unit.
2 Advantages and Disadvantages of Systematic Sampling
A = simple and quick to use, suitable for large populations.
D = sampling frame needed, can introduce bias
What is Stratified Sampling?
Sample size/Population size. Population divided into groups, and simple random samples carried out in each group.
2 Advantages and Disadvantages of Stratified Sampling
A = reflects population structure, guarantees proportional representation.
D = population must be clearly classified into strata, sampling frame needed.
What is Quota Sampling?
Populations are divided into groups according to characteristics. Tries to represent the entire population. Interviewer chooses individual sampling units.
2 Advantages and Disadvantages of Quota Sampling
A = no sampling frame required, allows for comparison between groups of the population.
D = can introduce bias, the population must be divided into groups.
What is Opportunity Sampling?
Sample taken from people available at the time of study who met criteria.
2 Advantages and Disadvantages of Opportunity Sampling
A = easy to carry out, inexpensive.
D = unlikely to provide a representative sample, highly dependent on individual researcher.
What is Daily Mean Wind speed measured in? 2 options
knots (kn) or Beauford Conversion
What is Daily Maximum Gust measured in?
knots (kn)
100
What is Daily Maximum Relative Humidity measured in?
percent (%)
8/8
What is Daily Mean Total Cloud measured in?
oktas
distance
What is Daily Mean Visibility measured in?
decimetres (dm)
