Chapter 5- Sampling and Probability

Question 1

What is random sampling?

Answer 1

Random sampling is one in which every member of the population has an equal chance of being selected into the study. Ideal and more likely to lead a representative sample. Expensive and difficult to achieve

Question 2

What is convenience sampling?

Answer 2

Convenience sampling is one that uses participants who are readily available. Less expensive and easier than random sampling. Used most often.

Question 3

What is generalizability?

Answer 3

Generalizability is the researchers ability to apply findings from one sample or in one context to other samples or contexts. Also called External Validity

Question 4

Explain the external validity principle

Answer 4

If you don’t have sufficient gernalizability, you can never be certain that results from your sample apply to the larger population.

Question 5

What is the goal of samples?

Answer 5

The goal of samples is to create a sample that represents our population of interest

Question 6

What is independent sampling?

Answer 6

Independent sampling means each person selected had no influence over other people selected

Question 7

If sampling is not random and independent, what can happen?

Answer 7

Resulting sample may be biased

Question 8

What is the difference between random sampling and random assignment?

Answer 8

Random sampling is the method participants are assigned to a sample; Random assignment is the method which individuals within a sample are assigned to a condition.

Question 9

What is a convenience sample?

Answer 9

Convenience sample consist of participants who are readily available. Convenience samples may not be generalizable to population. This method of sampling is used very often in social sciences.

Question 10

What is a volunteer sample?

Answer 10

Volunteer sample is when participants self-select themselves to be in a sample. Like convenience, they may not be generalizable to population

Question 11

What is replication?

Answer 11

Replication is doing the study again with different samples.

Question 12

What is a sampling error?

Answer 12

A sampling error is the discrepancy of what the sample looks like versus what the population looks like.

Question 13

What are inferential statistics?

Answer 13

Inferential statistics utilizes sample data to generalize to larger population. This is done by using probabilities.

Question 14

What is probability?

Answer 14

Probability is the likelihood something will occur out of all possible outcomes

Question 15

Why should we care about probabilities?

Answer 15

Probability theory helps us determine how likely are sample results are to occur given a hypothesis. Nothing is for certain and to make a conclusion

Question 16

What is personal probability?

Answer 16

Personal probability is the likelihood something will occur based on one’s opinion. Subjective

Question 17

What is expected relative-frequency probability?

Answer 17

Expected Relative frequency probability is the likelihood that an event will occur in the long run. A proportion of times the event occurs after many trials

Question 18

What is a trial?

Answer 18

A trial is each time a procedure occurs

Question 19

What is an outcome?

Answer 19

An outcome is the result of the trial

Question 20

What is success?

Answer 20

Success is when the outcome you were interested in occurs

Question 21

What is the law of large numbers?

Answer 21

The law of large numbers is as the numbers of the trials increase, our observed probability will approach the expected relative frequency probability

Question 22

Describe probability vs. proportion vs. percentage

Answer 22

Probability is the long term proportion; Proportion is the success divided by the total trials; Percentage is the probability or proportion multiplied by 100

Question 23

Individual trials must be independent. Explain this.

Answer 23

Independent means the outcome of each trial must not depend in any way on the outcome of previous trials. Each trial is independent from other trials

Question 24

What are 2 types of errors that can occur?

Answer 24

Type 1 and Type 2

Question 25

What is Type 1 error and Type 2 error?

Answer 25

The easiest way to think about Type 1 and Type 2 errors is in relation to medical tests. A type 1 error is where the person doesn’t have the disease, but the test says they do (false positive- REJECT THE NULL). A type 2 error is where the person has the disease but the test doesn’t pick it up (false negative- FAIL TO REJECT THE NULL).

Question 26

What is the null hypothesis?

Answer 26

Null hypothesis- it proposes that nothing will happen–nothing is going on.

Question 27

What is the alternate hypothesis?

Answer 27

The alternate hypothesis (research hypothesis) states there is a difference between populations, positive or negative. This is what the researcher anticipates