Chapter 7 Vocab

Question 1

Parameter

Answer 1

A number that describes some characteristic of the population in statistical practice. The value is usually not known because we cannot examine the entire population

Question 2

Statistic

Answer 2

A number that describes some characteristic of a sample. The value can be computed directly from the sample data. It is often used to estimate an unknown paramete

Question 3

Sampling variability

Answer 3

Describes how the value of a statistic varies in all possible samples from the population

Question 4

Sampling Distribution p̂

Answer 4

The distribution of values taken by the statistic in all possible samples of the same size from the same population

Question 5

Unbiased Estimator

Answer 5

A statistic used to estimate a parameter is an unbiased estimator if the mean of its sampling distribution is equal to the true value of the parameter being estimated

Question 6

Variability of a Statistic

Answer 6

Is described by the spread of its sampling distribution. This spread is determined primarily by the size of the random sample. Larger samples give smaller spread. The spread of the sampling distribution does not depend on the size of the population, as long as the population is at least 10 times larger than the sample.

Question 7

How does a sampling distribution of p̂ become approximately normal?

Answer 7

If n•p≥10 and n(1-p)≥10

Question 8

Central Limit Theorem

Answer 8

Says when n is large, the sampling distribution of the sample mean ẍ is approximately Normal.