Ch 9 Significance Tests

Question 1

Null hypothesis

-definition? -called? -symbol?

Answer 1

claim being tested
-sometimes called “status quo” hypothesis
represented by Ho

Question 2

Alternative hypothesis

-definition? -symbol?

Answer 2

other claim

represented by Ha

Question 3

define “rejecting the null hypothesis” or “evidence for the alternative hypothesis”

Answer 3

if you get an outcome that’s very unlikely to happen if Ho is true, then this is good evidence that the null is NOT TRUE

Question 4

step procedure for a significance test?

Answer 4

step -> hypothesis, significance level a, define parameter
plan-> same as ch. 8
do-> test statistic
conclude-> because..reject/fail to reject null, context

Question 5

what is the DO step really assessing?

Answer 5

assess how far the estimate is from the parameter, standardize the estimate
estimate-hypothesized value /
test statistic= standard deviation of estimate

Question 6

p value

Answer 6

probability computed assuming Ho is true, that the observed outcome would take as extreme or more extreme than that actually observed

(probability that measures the strength of evidence against Ho in favor of Ha) (probability that results happen given null is true)

Question 7

small p values are evidence against Ho because?

Answer 7

because they say that the observed result is UNLIKELY TO OCCUR when Ho is true
(large p values fail to give evidence against Ho)

Question 8

statistically significant

Answer 8

if p value is smaller than alpha -> reject null & say there’s convincing evidence in favor of alternative.

Question 9

“significant” means

Answer 9

means not likely to happen just by chance

rare, unusual, low probability

Question 10

under ____% is rare

Answer 10

5%

Question 11

alpha is usually what value?

Answer 11

.05 if unstated

Question 12

type 1 error

Answer 12

if we reject Ho when Ho is true

Question 13

type 2 error

Answer 13

if we fail to reject Ho when Ha is true

Question 14

significance level a is…

Answer 14

the probability of a type 1 error

Question 15

conditions for plan part, dealing w/ a population proportion

Answer 15

random
normal- npo & n(1-po)
independence- n * 10

Question 16

Do: what test is used from a population proportion?

Answer 16

1-prop z test

name p-value & z

Question 17

chance of type 1 error?

Answer 17

a

Question 18

chance of type 2 error?

Answer 18

b

Question 19

power

Answer 19

1-b

Question 20

3 ways to increase power

Answer 20

increase sample size
increase significance level (a) or decrease b
make Ha further away from Ho

Question 21

a

Answer 21

probability of type 1 error (rejecting Ho when you shouldnt bc Ho is true)

Question 22

b

Answer 22

probability of type 2 error (failing to reject Ho when you should because Ha is false)

Question 23

1-b

Answer 23

power, probability of rejecting Ho when you should bc Ho is true
-higher power -> more sensitive to the test, want good chance of correctly rejecting Ho

Question 24

a, b, 1-b, relationship?

Answer 24

a increase, b decreases -> inversely related
b decrease, power increase-> inversely related
a increase, power increase -> directly related (+ up to 1)

Question 25

knowing z score vs t score

Answer 25

z score- normcdf

t score- tcdf

Question 26

what is a significance test doing?

Answer 26

making a guess about a population w/ a sample

Question 27

do: what test for population mean?

Answer 27

t-test

name t, df, & p-value

Question 28

paired data

Answer 28

study designs that involve making 2 observations on the same individual, or 1 observation on each of 2 similar individuals yields this

Question 29

when do you use 1 sample t procedures?

Answer 29

after paired data, use to perform inference about the mean difference mD

Question 30

random selection

Answer 30

random selection from a population allows us to make an inference about the population

Question 31

random assignment

Answer 31

random assignment of subjects to treatments allows us to make cause & effect conclusion

Question 32

State step for paired data, what is the null usually?

Answer 32

null is usually set equal to 0