Chap 5: Selecting participants

Question 1

What is the sample size from which the improvement in accuracy slows dramatically?

Answer 1

30

Question 2

What is the difference between probability sampling and non probability sampling?

Answer 2

Probability sampling→ odds of selecting a particular individual are known and can be calculated
Nonprobability sampling→ odds of selecting a particular individual are not known

Question 3

What are the requirements for probability sampling?

Answer 3

Probability sampling→ odds of selecting a particular individual are known and can be calculated
- exact size of population is known
- each individual in the population must have a specified probability of selection
- selection must be random process

Question 4

What are the 6 types of probability sampling and describe each of them?

Answer 4

Simple random Sampling->Each individual in the pop has an equal chance of being selected and each selection is independent
Systematic sampling->Listing all the individuals in the population, then randomly picking a starting point on the list
Stratified Sampling->select equal-sized random samples from each of the pre-identified subgroups with random sampling
Proportionate stratified sampling->Determine what proportion of the population corresponds to each subgroup to have proportionate sample
Cluster Sampling-> Randomly select pre-existing groups instead of individuals
Combined-Strategy Sampling-> Researchers combine two or more sampling strategies

Question 5

How do we calculate the n in Systematic Sampling?

Answer 5

n=population size/desired sample size

Question 6

What are the three types of nonprobability sampling and describe them?

Answer 6

Convenience sampling-> Use participants who are easy to get and willing to participate
Quota sampling-> impose a quota of 15 girls and 15 boys instead of taking the first 30 students to volunteer
Snowball-> Using a current participant to reach other potential participants