26 terms

bias sample

Some members of the pop. of interest are more likely to be included in the sample

representative sample

All members of the population have an equal chance of being included in the sample

self-selection sampling (biased)

Sample has only people who volunteered to participate

cluster sampling (prob)

Clusters of participants w/i a population are randomly selected and all members are used

multistage sampling (prob)

2 random samples are selected: a random sample of clusters, then a random sample of people w/i the cluster

stratified random sampling (prob)

Researchers select demographic categories to represent % in population and uses random selection

oversampling (prob)

Researcher intentionally overrepresents one or more groups

oversampling (prob)

Researcher decides that 4% of the population isn't enough to be representative, so they sample 10%

systematic sampling (prob)

Researcher uses a computer or a random number table to select 2 random numbers

self-selected, convenience, snowball, purposive, quota

What are the 5 types of non-probability samples?

snowball sampling (biased)

Researchers find rare individuals and ask participants to bring friends (hard-to-access population)

quota sampling (biased)

Researcher identifies subsets in the population and sets a target number for each category

(80 African Americans, 80 Latinos)

(80 African Americans, 80 Latinos)

random sampling

What is most important for enhancing external validity?

1,000

What sample size is often cited as the optimal balance between accuracy and effort?

simple random, systematic, stratified, cluster, oversample, multistage sampling

What are the 6 types of probability sampling?

purposive sampling (biased)

If researchers want to study only certain kinds of people, they recruit only those participants

frequency claim

Typically, in which type of claim is it most important to have a random sample?

sampling error (random error)

No 2 samples will be the same; there's always variation

sample bias (random error)

Sample is systematically bias

Increase sample size, estimate using stats

How can you reduce sampling error?

sample bias (constant error)

Selected based on ease or any other systematic difference (self-selection)

sample isn't representative

Why does sample bias reduce external validity?

simple random sampling (prob)

Identify all members of the pop & randomly sample

high external validity

If you conduct a study w/i representative sample, you have...

oversampling

In which type of sampling

do researchers adjust final results?

do researchers adjust final results?

systematic sampling

Researcher starts with the 4th person and then count off every 7th person