Module 7

Question 1

What formal statements does hypothesis tetsing require?

Answer 1

null hypothesis and alternative hypothesis

Question 2

What is a null hypothesis?

Answer 2

a statement that is the skeptical viewpoint of your research question (the pattern you are interested in doesn’t exist)

Question 3

What is the alternative hypothesis?

Answer 3

a statement that is the positive viewpoint of your research question (the pattern you are interested exists)

contains everything that is not covered by the null hypothesis.

Question 4

What is Ho and Ha statement

Answer 4

Ho= null hypothesis
Ha= alternative hypothesis

Question 5

When creating the null hypothesis what must in include?

Answer 5

the equality statment. for example it says this amont and great/lesser (the crocidile sign with the line under)

Question 6

What is directionality?

Answer 6

refers to whether there is a direction in the null and alternative hypotheses in terms of the measurement variable

states that the difference should be in a specific direction

Question 7

What is a non directional hypotheses?

Answer 7

just states that there would be a difference in the alternative hypothesis, but does not say a specific direction

Question 8

What is the null distribution?

Answer 8

the sampling distribution that you would get if you repeatedly sampled from a fictious statistical population where the null hypothesis was true

Question 9

What is the statistical inference?

Answer 9

a statement about how likely it is that the sample you collected could have come from a statistical population where the null was true

Question 10

What are the four steps all statistical tests follow?

Answer 10

• define the null hypothesis and alternative hypothesis
• establish the null distribution
• conduct the statistical test
• draw scientific conclusions

Question 11

What does it mean that the null hypothesis and alternative hypothesis are mutually exclusive adn exhaustive?

Question 12

What ate the two possible outcomes that can come from conducting the statistical test?

Answer 12

• if it is likely that your data could come from the null distribution, then “we fail to reject the null hypothesis”
• if it is unlikely that your data could come from the null distribution, then “we reject the null hypothesis”

Question 13

What is hypothesis testing about comparing to?

Answer 13

the null hypothesis

Question 14

The null hypothesis can only be ________ not ______

Answer 14

can only be rejected, not accepted

Question 15

What are the two probabilities that a formal hypothesis is done using?

Answer 15

• Type 1 Error Rate (alpha)
• the p value

Question 16

What is the Type 1 Error Rate (alpha)?

Answer 16

• the probability of rejecting the null hypothesis when it is true
• we use it to decide the point where the data are sufficiently far from the null hypothesis that it should be rejected
• is set by the researcher without any reference to the data
• common to. be at 5%
  *

Question 17

What is the p value (p)?

Answer 17

• the probability of seeing your daya, or something more extreme, under the null hypothesis
• it is a probability under the null distribution
• determined by the data
• the area under the curve from the data to more extreme values

Question 18

What are the rules for making a statistical decision?

Answer 18

• if the p value is less than the Type 1 error rate (p<a) then reject the null hypothesis
• if the p value is greater than or equal to the Type 1 error rate (p>/=a) then we fail to reject the null hypothesis

Question 19

How do you make a scientific conclusion?

Answer 19

• take the statistical decision and connect it to the original research question

Question 20

What should a scientific statment include?

Answer 20

• strength of inference (want to acknowledge that your inference is only as good as the data, don’t say absolutes)
• effect size (only comes into play when the statistical decision is to reject the null hypothesis, refers to whether the observed difference is meaningful for the research question)

Question 21

What is an error rate?

Answer 21

the probability of making a mistake

Question 22

What are false negative and false positive rates?

Answer 22

False negative rate: a common term in medicine that refers to the rate that diagnostic tests are negative even when there is an underlying disease.

False positive rate: a common term in medicine that refers to the rate that diagnostic tests are positive even when there is no underlying disease.

Question 23

What are the two types of error rates in statistics?

Answer 23

• Type 1 errors
• Type II errors

Question 24

What are Type I errors?

Answer 24

• rejecting the null hypothesis when in fact it is true
• is a probability under the null distribution
• for hypothesis, it is under control of the researcher and is known as alpha (a)

Question 25

What is a Type II error?

Answer 25

• failing to reject the null hypothesis when in fact it is false
• is a probability under the alternative distribution
• for hypothesis testing, the alternative distribution is typically unknown, which means that the Type II error is also typically unknown

Question 26

What is a key distinction between the two error rates?

Answer 26

the Type I error rate is a probability under the null distribution, whereas the Type II error rate is a probability under the alternative distribution

Question 27

Tur or false: we can calculate the Type II error rate

Answer 27

false, we can not calculate ti

Question 28

What happens to the Type II error rate when the Type I error rate decreases?

Answer 28

increases (and vise versa)