Chapter 5

Question 1

Sampling

Answer 1

The way we choose who participates in our study

Question 2

Types of Sampling

Answer 2

Probability

Non probability

Question 3

Probability sampling

Answer 3

you are able to explain the possibility (percentage)that any individuals has for becoming a participants

Question 4

Random Sampling

Answer 4

every individual in the population has a equal chance of being selected
Why is this not always possible??
  -time consuming
  -difficult
  -costly

Question 5

Representative samples

Answer 5

• “Represents” the larger population
• Looks like the population, only smaller
• Creates sampling error
• Need to keep in mind margin of error

Question 6

Fours basic type of probability sampling

Answer 6

• Simple random sampling
• Systematic sampling
• Stratified random sampling
• Cluster sampling

Question 7

Simple Random Sampling

Answer 7

Every possible sample (from the total population) has the same chance of being selected
Example: If I wanted to ask 30 VCU students to report their college experience, I would first narrow a course at VCU and every student from that course would have the same chance of being chosen
-sampling frame: list of all possible participants in a population
- VCU
One problem: need to know exactly how many people are in a given population

During our study, we might not know the number of students who are attending class that day

Question 8

Systematic Sampling

Answer 8

Choosing every nth person from a sample
-students every other person
Problem: not every person in the sample has equal likelihood of becoming a participant

Question 9

Stratified Random Sampling

Answer 9

-Divide the population into strata before conducting simple random sampling
-Vcu female students
-Vcu male students
-Sometimes done with proportionate sampling
-Helps in examining differences across different groups – helps improve representativeness (and, generalizability)
-Before choosing participants, you choose groupings of individuals
Geographically
By institutions

Can do this with a multi-stage cluster sampling method
Randomly choose state
Randomly choose counties
Randomly choose schools
Randomly choose participants

Advantages:
Don’t need a sampling frame (i.e., don’t need to know every possible participant)
Less time and effort

***strata also done with proportionate sampling.

Question 10

Nonprobability

Answer 10

Don’t know the probability that an individual was chosen from a particular population
-Can’t calculate error of estimation

Question 11

Three types of non-probablity

Answer 11

Convenience
Quota
Purposive

Question 12

Convenience Sampling

Answer 12

-Participants are easy to obtain
(psy 101 students)
-Makes generalizability more difficult
-Makes it easy for us to test hypotheses about variables
(nice people should donate money)
-Used because we aren’t typically trying to describe a population

Question 13

Quota Sampling

Answer 13

Convenience sample that ensures certain types of people are included in the study
Example: If we’re interested in the number of shoes people own, and we think it might be different for males versus females, then we should make sure there are equal numbers in our sample

Question 14

Purposive Sampling

Answer 14

Using past research to tell you who to sample

Should not generally be used

E.g., Ohio residents predict Presidency?

Question 15

problems with sampling

Answer 15

-Who chooses to respond
-What you are asking about
-Individual differences
Language
Literacy
Owning technology
-Amount of compensation

Question 16

What can we do?

Answer 16

increase power – ability to detect effects

 - Do this by increasing the number of participants
 - Smaller effects require more participants to detect an effect
 - For a Cohen’s d = .2, need about 200 participants for adequate power * *Effect is how important/how much the variable matters