GEO E111 Lecture Notes - Lecture 25: Systematic Sampling, Stratified Sampling
Document Summary
Selection of members of a group haphazardly where every item has an equal chance of being selected e. g. to select 5 students to go for a tour from a class: Class members write their names on pieces of paper. They are folded and put in a basket. The basket is shaken and fives papers are taken out: systematic sampling. Selection of members of a sample from an evenly distributed phenomena at regular intervals e. g. after every 10 items/members: stratified sampling. Selection of members of a sample by breaking the population into homogenous groups e. g. to select 6 students to go for a tour: Select 3 student from each group by random or systematic sampling. Combine units from each group to form the required sample: cluster sampling. Advantages: it"s less expensive, it saves time, it avoids bias. Disadvantages: a poor selected sample can lead to misleading information, systematic sampling to an evenly distributed population.
