AP Stats - Unit 7 Vocab

Parameter

A number that describes some characteristic of the population

Statistic

Number that describes some characteristic of a sample

Sampling variability

The value of a statistic varies in repeated random sampling

Sampling distribution

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

Unbiased estimator

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

Variability (of a statistic)

Spread of a statistics sampling distribution. Statistics from larger samples have less variability

Sample proportion ("p hat")

As "n" increases, the sampling distribution of "p hat" becomes approximately normal. Before you perform normal calculations, check that the large counts condition is satisfied

Sampling distribution of "P hat"

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

Mean of the sampling distribution of. "P hat"

The probability of something happening, mean of "p hat" = p

Standard deviation of the sampling distribution of "p hat"

1/n√np(1-p)

Approximately normal

When the distribution follows a normal curve.

Sample mean "x bar"

μx̄=μ

Sampling distribution of "x bar"

If the population has a normal distribution, then the sampling distribution of "x bar"also has a normal distribution

Mean of the distribution of "x bar"

μx̄=μ

Standard deviation of the sampling distribution of "x bar"

σx̄=σ/√n

Central limit theorem

In an SIRS of size "n" from any population with mean μ and finite standard deviation σ, when "n" is large, the sampling distribution of the sample mean x̄ is approximately normal.