Prelim #2

Question 1

Types of Test

Answer 1

Test of a single proportion
Goodness of fit test
Test of association

Question 2

null/reference distribution of a test of single proportion

Answer 2

binomial distribution

Question 3

null/reference distribution of goodness of fit test

Answer 3

chi-square distribution

Question 4

null/reference distribution of a test of association

Answer 4

chi-square distribution

Question 5

assumptions for chi-square test

Answer 5

• adequate cell sizes
• all cells must have expected counts >=1
• at least 80% of the cells need expected counts>=5

Question 6

assumptions for binomial distribution

Answer 6

• the number of trials, n, is fixed
• individual trials are independent
• there are only 2 outcomes for every trial
• the probability of success (p) is the same for every trial

Question 7

assumptions of poisson distribution

Answer 7

-observations are independent and the probability of an observation is constant throughout

Question 8

clumped

Answer 8

variance>mean

Question 9

odds ratio

Answer 9

a/c/b/d (odds of success in one group divided by the odds of success in another group)

Question 10

relative risk

Answer 10

pr(worse outcome in group 1)/pr(worse outcome in group 2)

Question 11

finding p value in R

Answer 11

1-pchisq(teststat, df)

Question 12

finding critical value in R

Answer 12

qchisq(percentile, df)

Question 13

Type 1 error

Answer 13

rejecting a true null hypothesis

Question 14

Type 2 error

Answer 14

(beta) failing to reject a false null hypothesis

Question 15

hypothesis testing assumes that…

Answer 15

sampling is random

Question 16

if test statistic is >critical value

Answer 16

reject null

Question 17

if p-value is <0.05

Answer 17

reject null

Question 18

significance level

Answer 18

the probability used as a criterion for rejecting the null hypothesis

Question 19

null distribution

Answer 19

the distribution of the test statistic, when assuming that the null hypothesis is true

Question 20

if odds ratio confidence interval contains 1?

Answer 20

no association

Question 21

if odds ratio does not contain 1?

Answer 21

statistically significant association

Question 22

standard error of the mean formula

Answer 22

sd/sqrt(n)

Question 23

CI for sample mean

Answer 23

sample mean +/- 2 SE

Question 24

power

Answer 24

the ability of a test to reject a false null hypothesis

1-beta

Question 25

the smaller beta (type 2 error)…

Answer 25

the more power a test has

Question 26

a larger sample gives more/less power?

Answer 26

more

Question 27

dispersed

Answer 27

variance is less than mean

Question 28

p-value

Answer 28

The probability of getting the result, or something as unusual or more unusual, if the null hypothesis were true