Population
The entire group of individuals
Census
Data from all of the population
Sample
A subset of the population
Convenience sample
Easy-to-reach sample (first 100 people that walk into a store, your entire first period class)
Voluntary response sample
Open invitation to join the sample (a mail-in survey sent to everyone in the district for people to choose whether they want to complete the form or not)
Random sample
Chance process to select random individuals
Simple random sample
The simplest method to choosing a random sample
Stratified random sample
More complex method of random sampling where a population is divided into similar groups (called strata), and a select few from each group is chosen. This guarantees some level of representation which helps to bring more accurate data.
Cluster sample
Sampling based on location, into groups of clusters.
Systematic random sample
More methodic method of random sampling, where every nth member is chosen
Inference
Conclusions drawn from samples
Margin of error
Binds likely errors
Undercoverage
Some of the population isnāt represented or cannot be chosen (sampling error). For example, older people are less likely to have mobile phones, so a survey carried out by calling mobile phone numbers will not properly represent the older generation.
Nonresponse
Some of the samples do not participate. If the sample is ALREADY chosen, and people ACTIVELY choose not to send in their response.
Voluntary response bias
People can CHOOSE to be part of the sample. This makes the data collected more extreme, as people with more middle-ground views will not feel strongly and take the time to respond.
Response bias
Systematic pattern of incorrect responses. (People will say to a survey they do not do drugs in fear of