sampling methods stats

SRS

Every possible sample of a given size has an equal chance of being selected, every individual of the population has an equal chance of being selected, typically done using a random number generator or drawing names from a hat, good, label individuals numbered all the words from 1- the amount, randomize use calculator to generate random numbers like data that could respond to picked choosing a group from the population, so that every individual and every group of individuals is equally likely to be chosen

Stratified

The population in first divided in the homogeneous groups called strata base on some shared, characteristic, a.k.a. age groups, gender income levels, then an SRS is drawn from within each stratum insures representation, can be by row or by column choose a SRS from each Stratus

Cluster

The population is divided in the hetero, genus groups called clusters, often geographically-based neighborhoods schools, a random samples of clusters is selected, all individuals within the selected clusters are included in the sample, useful when populations are large, and geographically dispersed, Rose can be clusters. Each row is numbered downwards, one to five at least then generate one random number from one to five then collective. Different. They are mini populations, randomly selects groups, and sample everyone in the group.

Convenience

Individuals are selected based on their easy accessibility and willingness to participate, highly prone to bias, as it may not represent the population

Symmetric

Individuals are selected from a List at regular intervals, a random starting point is chosen then every individual is selected every 10th person the interval is calculated as population size over sample size choose a random starting point use equal intervals to move i

To the next individual until you have as many as you need Say they wanna sample every eighth fan first you need to figure out the starting fan randomly select the fan in market with X then generate one random number fan from one to 80 starting with that person begin marking every eighth seat until you get a sample of 10 seats start back at the beginning if you need to

Voluntary

Individuals who solve selects to participate in the sample a.k.a. online polls Call in surveys often biased because people are strong opinions either positive or negative are more likely to respond

Under coverage

Occurs when some members of the population are symmetrically excluded from the sampling frame the list from which the sample is drawn, example a phone survey that excludes people without landline or cell phones depending on the focus

Nonresponse

Occurs when selected individuals cannot be contacted or refused to participate in the survey. If the non-responders differ symmetrically from the responders, the results will be bias example a survey about exercise habits where fewer cough potatoes respond

Response bias

occurs when respondents provide an accurate or misleading answers can be caused by social disability bias, tendency to answer in a way that is perceived favorably, interviewer bias, the way, an interviewer ask questions, or their demeanor, influences responses, memory bias, an accurate recall of past events