Chapter 7: Sampling

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

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

Sample has only people who volunteered to participate

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

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

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

Researcher intentionally overrepresents one or more groups

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

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

What are the 5 types of non-probability samples?

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

Researcher identifies subsets in the population and sets a target number for each category (80 African Americans, 80 Latinos)

What is most important for enhancing external validity?

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

What are the 6 types of probability sampling?

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

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

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

Sample is systematically bias

How can you reduce sampling error?

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

Why does sample bias reduce external validity?

Identify all members of the pop & randomly sample

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

In which type of sampling do researchers adjust final results?

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