Chapter 7: Confidence Intervals

Question 1

What is a confidence interval?

Answer 1

Specifies range of values to estimate location of unknown pop parameter

Question 2

What does the margin of error accompany?

Answer 2

Confidence level

Question 3

What does the confidence level tell us?

Answer 3

How likely our parameter is to lie within that interval

Question 4

What does the confidence level and margin of error together tell us?

Answer 4

How accurate our estimate is likely to be

Question 5

What is a point estimate?

Answer 5

Single statistic used as best estimate or a alike parameter

Question 6

What does accuracy refer to?

Answer 6

Freedom from error

Question 7

What is freedom from error?

Answer 7

Estimate differs from parameter of interests value

Question 8

What is the interval estimate?

Answer 8

Range of values parameter is likely to fall

Question 9

What is the essence of sampling theory?

Answer 9

Probability sample will yield results that closely resemble those if we measured whole pop

Question 10

What is a probability sample?

Answer 10

Every element known prob of being selected

Question 11

What does the law of large numbers tell us?

Answer 11

With large sample, sample statistics approximate pop parameters very closely

Question 12

What does a confidence level specify?

Answer 12

Probability that our particular sample will contain pop parameter

Question 13

What happens with higher confidence levels?

Answer 13

lower the risk that interval estimate doesn’t have parameter

Question 14

What happens with a lower confidence level?

Answer 14

Increases risk interval estimate doesn’t have parameter

Question 15

What happens in the case of the 99% confidence interval?

Answer 15

99% of all samples drawn from the same population with same measure at same time will be ± amount of sampling error

Question 16

What would a correct interpretation look like?

Answer 16

95% confident that our interval estimate of 150 to 165 pounds will in fact contain the true population value.

Question 17

What do confidence interval statements actually mean?

Answer 17

we would expect to fail to capture the population mean in 5% of our samples (95)

Question 18

What does a confidence interval specify?

Answer 18

Range of values that we estimate an unknown population parameter will fall

Question 19

What does a confidence level specify?

Answer 19

Probability that population parameter will lie within that range

Question 20

What happens with interval width and level of confidence?

Answer 20

Higher confidence level, wider confidence interval will be

Question 21

What is the sampling error?

Answer 21

Whenever a sample rather than entire population is measured

Question 22

What is the margin of error?

Answer 22

Estimate amount of difference that we think is possible between our statistic and corresponding parameter

Question 23

What is the relationship between margin of error and sampling error?

Answer 23

How much sampling error we think is possible for given statistic

Question 24

What is confidence interval effected by?

Answer 24

Amount of variation in pop, sample size

Question 25

What happens with a greater sample size?

Answer 25

Smaller SD and smaller margin of error and sampling error

Question 26

What is the central limit theorem?

Answer 26

With repeated samples sampling distribution will eventually become normal

Question 27

What is a theoretical distribution?

Answer 27

Idea of conducting repeated samples infinitely

Question 28

What are the two assumptions you need to calculate a confidence interval?

Answer 28

Used random sampling, normal distribution

Question 29

What is the first scenario for calculating confidence interval?

Answer 29

Known pop sd

Question 30

What are the elements of the first scenario for calculating confidence interval?

Answer 30

Use z and normal distribution to get critical value, use o to get standard error

Question 31

What is the second scenario for calculating confidence interval?

Answer 31

Large sample and unknown pop sd

Question 32

What are the elements of the second scenario of calculating confidence interval?

Answer 32

Use z and normal distribution to get critical value, use s to estimate o for standard error

Question 33

What is the third scenario for calculating confidence interval?

Answer 33

Small sample and unknown pop sd

Question 34

What are the elements for the third scenario of calculating confidence interval?

Answer 34

Use t and t-distribution to determine critical value, use s to estimate o for standard error