Inferential statistics Flashcards
Define Stable:
Results will always change across the sample but when stable it does not change as much.
What is inferential statistics?
Use sample statistics t estimate population paramater. I.e. true value in population. So Ybar (sample mean) is an estimate of mu (population parameter).
Describe the estimator property of unbiasedness.
An estimator is unbiased if the mean of the sampling distribution of the estimator equals the population parameter.
What is a sampling distribution?
A frequency distribution of a statistic, as opposed to a raw score.
What is a sampling distribution of the mean?
The sampling distribution of the mean is a frequency distribution of sample means.
What is the sampling distribution of the median?
A frequency distribution of sample medians.
Describe how an estimator is unbiased:
If its average value over all possible random samples is exactly (emphasis added) the population value. So E(Ybar) = mu
Over all possible samples of size n, the mean of all the possible sample means = mu. Therefore, the Ybar is an unbiased estimator of the population mean.
Over all possible samples of size n, the mean of all the possible sample means = mu. Therefore, the Ybar is an unbiased estimator of the population mean.
What is the mean sensitive to?
Extreme scores.
Is the sample median an unbiased estimate of the population mean?
Yes.
When is an estimator consistent?
An estimate is consistent if, as n increases, the difference between the estimator and the population parameter approaches zero.
What happens tothe distribution when n increases?
It becomes narrower or more peaked. Shows that the median is a consistent estimator. So is the mean.
How do you tell which estimator is more efficient?
Given two unbiased estimators, say the mean and median, the more efficient estimator has a smaller sampling variance. i.e. standard error.
The wider your standard deviation, the wider your…
graph
Which is a more efficient estimator? The mean or the median?
The mean.
