Interval Estimates Flashcards
What is a confidence interval
An interval estimate provides a range of numbers that with a certain level of confidence contains the population parameter of interest
What is the requirement for constructing a confidence interval
That the distribution is normal
What is a margin of error
The upper and lower distance from a point estimate making up the confidence interval
Why is it not correct to say that there is a chance the population mean lies within an interval
Because the population mean does not vary, the interval does depending in the samples that construct it
What is the significance level
Denoted by a it is the likelihood that the confidence interval foes not contain the sought after parameter
What is the confidence coefficient
The likelyhood that the sought after parameter lies somewhere within the confidence interval denoted (1-a) because it is the inverse of the significance level
What is the confidence level
The confidence coefficient in percent
What forces the confidence interval to he wider
Larger population standard deviation, smaller sample size and greater desired confidence level
What is the t distribution
A variant of the normal z distribution with a slightly wider tail and the tails width is determined by the degree of freedom
How foes the t distribution look when the degree of freedom approaches infinity
Like the z distribution
When is the required sample size the largest when estimating population proportion
When p = .5 aka when she success rate is equal to the failure rate
What is a point estimator
The sample equivalent of a population parameter. It provides a single variable that is an estimate of the variable in question
