Question

If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect

A. | the required sample size to increase | ||

B. | the UCL - LCL range to decrease | ||

C. | precision of the estimate to decrease | ||

D. | precision of the estimate to increase |

Answer #1

For a greater confidence level, the critical z value increases, and thus the margin of error also increases. The confidence level itself dont have any relation to the sample size.

Lower confidence level, decreases the margin of error and therefore the width of the confidence interval also become narrower. Therefore the precision also increases with lower confidence level. As we increase the confidence level to 99% here, therefore the margin of error increases, interval width widens and hence the precision decreases.

**Therefore C is the correct answer here.**

If a confidence interval is constructed at a confidence level of 99% instead of 95%:
a)Estimation precision decreases
b)The precision of the estimate is not altered
c)We can accurately calculate the value of the parameter of interest
d)Estimation accuracy improves significantly

A 99% confidence interval estimate of the population mean ? can
be interpreted to mean:
a) if all possible sample are taken and confidence intervals
created, 99% of them would include the true population mean
somewhere within their interval.
b) we have 99% confidence that we have selected a sample whose
interval does include the population mean.
c) we estimate that the population mean falls between the lower
and upper confidence limits, and this type of estimator is correct
99%...

How will the width of a confidence interval change (if at all)
in each of the following cases?
A) Sample standard deviation decreases:
a) increase
b) decrease c) stay
the same
B) Sample size decreases:
a) increase
b) decrease
c) stay the same
C) You change from a 95% CI to a 99% CI:
a) increase
b) decrease
c) stay the same

We want to estimate with 99 percent confidence the percentage of
buyers of cars who are under 30 years of age. A margin of error of
5 percentage points is desired. What sample size is needed? In an
earlier sample, we found a 99 percent confidence interval of buyers
under 30 years of age to be [.18, .27].
A. 104
B. 392
C. 523
D.664

A 99 percent confidence interval has higher confidence but less
precision than a 95 percent confidence interval.
True or False

Q10. If population mean is included in the 95% confidence
interval then
a. 99% confidence interval will always include the mean
b. 90% confidence interval will never include that mean
c. 99% confidence interval will never include that mean
d. 90% confidence interval will always include the mean

Which of the following statements is true?
The 95% confidence interval is wider than the 99% confidence
interval.
The ONLY way to reduce the width of a confidence interval is to
reduce the confidence level.
The required sample size for a population mean is ONLY
dependent on population variance.
Given population variance and sampling error, higher confidence
level results in larger sample size.

A
95%
confidence interval of
16.6
months to
49.6
months has been found for the mean duration of
imprisonment,
muμ,
of political prisoners of a certain country with chronic
PTSD.
a. Determine the margin of error, E.
b. Explain the meaning of E in this context in terms of the
accuracy of the estimate.
c. Find the sample size required to have a margin of error
of
12
months and a
99%
confidence level. (Use
sigmaσequals=42
months.)d. Find a
99%...

A manager wishes to estimate a population mean using a 99%
confidence interval estimate that has a margin of error of plus or
minus±48.0 If the population standard deviation is thought to be
630, what is the required sample size?
The sample size must be at least?

1. From the following confidence interval for µ1 - µ2: [-0.32,
0.86], the following can be concluded
Select one:
a) That there is no significant difference between the means of
both populations
b)That both stockings are small
c)That µ2 is greater than µ1
d)That µ1 is greater than µ2
2. If a confidence interval is constructed at a confidence level
of 99% instead of 95%
Select one:
a)Estimation precision decreases
b)The precision of the estimate is not altered
c)Estimation accuracy...

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