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When the population is normally distributed population standard deviation s is unknown and the sample size is n equals 15 the confidence interval for the population mean s is based on the?
Wiki User
∙ 10y ago
The Z test.
Wiki User
∙ 10y ago
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What happens to the confidence interval as the standard deviation of a distribution increases?
The standard deviation is used in the numerator of the margin of error calculation. As the standard deviation increases, the margin of error increases; therefore the confidence interval width increases. So, the confidence interval gets wider.
What does a 95 percent confidence interval tell you about the population proportion?
There is a 95% probability that the true population proportion lies within the confidence interval.
When the population standard deviation is unknown and the sample size is less than 30 what table value should be used in computing a confidence interval for a mean?
t-test for means
If the standard deviation is doubled what will be the effect on the confidence interval?
The confidence intervals will increase. How much it will increase depends on whether the underlying probability model is additive or multiplicative.
When comparing the 95 percent confidence and prediction intervals for a given regression analysis what is the relation between confidence and prediction interval?
Confidence interval considers the entire data series to fix the band width with mean and standard deviation considers the present data where as prediction interval is for independent value and for future values.
What effect increasing only the population standard deviation will have on the width of the confidence interval?
It will make it wider.
When the sample size and sample standard deviation remain the same a 99 percent confidence interval for a population mean will be narrower than the 95 percent confidence interval for the mean?
Never!
What happen to confidence interval if increase sample size and population standard deviation simultanesous?
The increase in sample size will reduce the confidence interval. The increase in standard deviation will increase the confidence interval. The confidence interval is not based on a linear function so the overall effect will require some calculations based on the levels before and after these changes. It would depend on the relative rates at which the change in sample size and change in standard deviation occurred. If the sample size increased more quickly than then standard deviation, in some sense, then the size of the confidence interval would decrease. Conversely, if the standard deviation increased more quickly than the sample size, in some sense, then the size of the confidence interval would increase.
What happens to the confidence interval as the standard deviation of a distribution increases?
The standard deviation is used in the numerator of the margin of error calculation. As the standard deviation increases, the margin of error increases; therefore the confidence interval width increases. So, the confidence interval gets wider.
When population distribution is right skewed is the interval still valid?
You probably mean the confidence interval. When you construct a confidence interval it has a percentage coverage that is based on assumptions about the population distribution. If the population distribution is skewed there is reason to believe that (a) the statistics upon which the interval are based (namely the mean and standard deviation) might well be biased, and (b) the confidence interval will not accurately cover the population value as accurately or symmetrically as expected.
Is it true that the larger the standard deviation the wider the confidence interval?
no
What happens to the confidence interval as the standard deviation of a distribution decreases?
It goes up.
What does a confidence interval for a population mean constructed from sample data show?
A confidence interval of x% is an interval such that there is an x% probability that the true population mean lies within the interval.
What does a 95 percent confidence interval tell you about the population proportion?
There is a 95% probability that the true population proportion lies within the confidence interval.
What percentage of time will the population proportion not be found within the confidence interval?
What percentage of times will the mean (population proportion) not be found within the confidence interval?
When the population standard deviation is unknown and the sample size is less than 30 what table value should be used in computing a confidence interval for a mean?
t-test for means
How do you calculate the parameter to a 99.9 confidence interval using mean and standard deviation?
Did you mean, "How do you calculate the 99.9 % confidence interval to a parameter using the mean and the standard deviation?" ? The parameter is the population mean μ. Let xbar and s denote the sample mean and the sample standard deviation. The formula for a 99.9% confidence limit for μ is xbar - 3.08 s / √n and xbar + 3.08 s / √n where xbar is the sample mean, n the sample size and s the sample standard deviation. 3.08 comes from a Normal probability table.
