Maths Unit 2 Flashcards
What is the definition of Population
The entire group being considered
What is the definition of a Sample
A subset of the population
What is the definition of a Census
When we survey the entire population, this is rare and expensive
What is the definition of Bias
A systematic error. It is when a sample is over-representative of a particular group
What is the definition of Variables
The attributes of the object under consideration; may be qualitative or quantitative
What is the definition of Qualitative
Variables that can’t be counted
What is the definition of Quantitative
Variables that can be counted or measured. Split into discrete or continous data
What is the definition of Discrete Data
Only takes exact values e.g. Shoe size
What is the definition of Continous Data
Measured on a scale and can take any value within that scale e.g. Height
What are all the types of sampling
1) Simple Random
2) Systematic
3) Stratified
4) Cluster
5) Opportunity
6) Quota
7) Self-selected
What are the advantages of Simple Random Sampling
1) Easy to implement
2) Each member of the population has an equal chance of being chosen
3) Free from bias
What are the disadvantages of Simple Random Sampling
1) If sampling frame is very large it may be impractical
2) A complete list of the population may not be available
3) Minority subgroups may not be present in the sample
What are the advantages of Systematic Sampling
1) Easy to select
2) Evenly spread over the population
What are the disadvantages of Systematic Sampling
1) Not all data has an opportunity to be selected
2) Bias may be present if a certain trait occurs periodically
What are the advantages of Stratified Sampling
1) Strata are proportionally represented in the final sample
2) Easy to compare subgroups
What are the disadvantages of Stratified Sampling
1) Information must be gathered before subgroups can be chosen
2) It may not always be possible to split a population into mutually exclusive subgroups
What are the advantages of Cluster Sampling
1) Cuts down the cost an time by collecting data from only a limited number of groups
2) Can show grouped variations
What are the disadvantages of Cluster Sampling
1) It is not a genuine random sample
2) The sample size is smaller and from thus the sample is likely to be less representative of the population
What are the advantages of Opportunity Sampling
1) Cuts down the cost of preparing a sampling frame as it is less time-consuming
What are the disadvantages of Opportunity Sampling
1) Bias, as it does not represent the population well
What are the advantages of Quota sampling
1) Does not require a sampling frame or strict random sampling technique, which makes t quicker
2) Accurately represents the entire population (Among random sampling methods)
3) Easier comparison between subgroups
What are the disadvantages of Quota Sampling
1) Can have selection bias as the researcher decides who is included
2) Not always possible to divide the population into mutually exclusive groups
3) Inaccuracy is very possible
What are the advantages of Self-selected sample
1) Very low cost and low effort
What are the disadvantages of Self-selected sampling
1) Bias is very likely
