BUSN

Question 1

SE for mean

Answer 1

s/(sqrt of n)

Question 1

SE for proportions

Answer 1

sqrt of [p(1-p)/n]

Question 2

the collection of ˆy is called

Answer 2

sampling distribution
-it is a t-distribution

Question 3

degrees of freedom

Answer 3

DF=n-1
-use degrees of freedom to specify how close the t-curve is to the normal curve

Question 4

mean

Answer 4

true population mean, u

Question 5

standard deviation

Answer 5

standard error of yˆ,
s/(sqrt of n)

Question 6

SE(Y)

Answer 6

the average error between a sample yˆ and the true u

Question 7

t curve

Answer 7

-also bell shaped
-longer tails than normal (z-curve)
-uncertainty in not knowing true std. dev
-wider confidence intervals

-*use t-curve to estimate the population (true) average “u”, based on the sample average yˆ

Question 8

Confidence interval (proportions)

Answer 8

pˆ± ME

(ME= z* * SE)

Question 9

Confidence intervals (means)

Answer 9

yˆ± ME

(ME= t* * SE)

Question 10

Interpretation of CI for mean

Answer 10

There is 95% confidence that the true average ___ “u” is between ___ and ____

-the average is within the range

Question 11

95% confidence meaning

Answer 11

if we took a large number of random samples, the true average would be inside 95% of these intervals

Question 12

test statistic (proportion)

Answer 12

(pˆ - Ho )÷ SE

Question 13

test statistic (mean)

Answer 13

(yˆ-µ) ÷ SE

Question 14

t score data size

Answer 14

n ≥ 30

*if normal distribution sample size can be less than 30

Question 15

sample size formula for means

Answer 15

n= ((t**s)÷(ME))ˆ2

*for large sample sizes use z instead of t

Question 16

sample size formula for proportions

Answer 16

n= (z*/ME)ˆ2 * p(1-p)

Question 17

the collection of pˆ

Answer 17

sampling distribution of pˆ

Question 18

sample size requirements (proportion)

Answer 18

np≥ 10 and n(1-p) ≥ 10

Question 19

95% meaning (proportion)

Answer 19

95% of samples will have pˆwithin two standard errors of the true p

-95% of the time, the true parameter p will be within 1.96 standard errors of the sample result pˆ

Question 20

critical value

Answer 20

z

Question 21

confidence interval interpretation (proportion)

Answer 21

we are 95% confident the true proportion of customers is between ____ and ____

-captures true p from the whole population

-95% of intervals is successful in capturing the true p

Question 22

the more confident we want to be about capturing true p

Answer 22

the wider the interval needs to be

-very confident p is inside a wide interval
* too wide it won’t be useful

Question 23

99% vs 90% vs 95%

Answer 23

• 99% is usually too wide to be useful

-90% doesn’t have a very high success rate

-95% usually provides a god compromise between not being to wide

Question 24

the wider the interval

Answer 24

• the larger the margin of error

Question 25

the margin of error (proportion)

Answer 25

gives the maximum error between p and pˆ for the given confidence

Question 26

ME is half

Answer 26

the interval width

Question 27

if previous studies suggest a certain value of p

Answer 27

then use it

Question 28

if no previous p is available

Answer 28

use p=.5

Question 29

if ho is inside the interval

Answer 29

we cannot reject it

-there is insufficient evidence to reject Ho

-p-value> a

Question 30

if Ho is outside the interval

Answer 30

we can reject it

-there is sufficient evidence to reject Ho

-p-value < a

Question 31

IMPLICATIONS

Answer 31

90% INTERVAL: a=.1

95% INTERVAL: a=.05

99% INTERVAL: a=.01

Question 32

Small p-value e.g .002

Answer 32

-sufficient evidence to reject Ho

-sufficient evidence to conclude Ha

-Ho-value is OUTSIDE confidence interval

Question 33

large p-value e.g .36

Answer 33

-Insufficient evidence to reject Ho

-Insufficient evidence to conclude Ha

-Ho value is INSIDE confidence interval

Question 34

Large test statistic e.g 2 or 3 (proportion)

Answer 34

-pˆ is far from p

-strong evidence in favor of Ha

-likely reject H0

Question 35

p-value < a

Answer 35

-sufficient evidence to conclude Ha (Reject Ho)

Question 36

p-value > a

Answer 36

insufficient evidence to conclude Ha (DONT reject Ho)

Question 37

Significance level

Answer 37

a is a value used as a cutoff for deciding how small a p value needs to be to provide convincing evidence against Ha

Question 38

Small p-value

Answer 38

large test statistic

pˆ very far from p

p is low Ho must go

Question 39

Large p-value

Answer 39

small test statistic

pˆ reasonably close to p

if the p is high, Ho survive

Question 40

Type 1 error

Answer 40

Ho is TRUE, but we choose Ha

can be reduced using a=.01 (make it harder to reject Ho)

type 1: the first listed (1: Ho) is TRUE

Question 41

Type 2 error

Answer 41

Ha is true, but we choose Ho

can be reduced using a=.10 (make easier to reject Ho)

Type 2: the second listed (2: Ha) is TRUE