Chapter 1 - Data Collection Flashcards
Census definition (adv and dis)
A survey that observed every member of a population.
Advantages:
Completely accurate
Disadvantages;
Time consuming, expensive, hard to process large quantities of data
Sample definition (adv and dis)
A selection of observations taken from a subset of the population used to find out about the whole population.
Advantages: Less time consuming, cheaper, less data to process.
Disadvantages: Less accurate data, sample may not be large enough to give information about small subgroups of the population.
Simple random sampling (adv and dis)
A randomly picked sample of people
Advantages: Unbiased, easy and cheap.
Disadvantages: Not suitable for large samples and populations, sampling frame needed.
Systematic sampling (adv and dis)
Sampling units are chosen at regular intervals in an ordered list (sampling frame). The first is chosen randomly and intervals are taken from there.
Advantages: simple and quick, suitable for large samples and populations.
Disadvantages: Sampling frame needed, which can introduce bias if not random.
Stratified sampling (adv and dis)
Population is divided into mutually exclusive strata and a random sample is taken from each.
Number in group sampled = number in group / number in population, multiplied by sample size.
Round to nearest integer if not a whole number.
Use a random number generator to select the units from the amount found.
Advantages: sample accurately reflects population structure, and proportional representation occurs.
Disadvantages: population must be clearly classified into distinct strata, + same as simple random sampling
Convenience sampling (adv and dis)
Sample is taken from people available at the time and who fits the criteria of people you’re looking for
Advantages: Easy and cheap
Disadvantages: Biased, unlikely to provide a representative amount
Types of data
Quantitative: data associated with numerical observations.
Qualitative: data associated with non numerical observations.
Discrete variable: can only take specific values
Continuous variable: can take any value
