Statistics ch 7

To estimate the necessary sample size when no value of p^ is available, we use p^=_

0.5

When constructing a confidence interval for a population mean u from a sample of size 12, the number of degrees of freedom for the critical value ta/2 is_

11

The margin of error is the product of the standard error and the _

Critical value

If a 95% confidence interval for a population mean is 1.7<U<2.4, then the probability is 0.95 that the mean is between 1.7 and 2.3

False

The margin of error does not depend of sample size

False does

The student's t curve is less spread out than the standard normal curve.

False more

To construct a confidence interval for a population mean, we add and subtract the critical value from the point estimate

False, margin of error

If we increase the confidence level and keep the sample size the same, we _ the margin of error

Increase

In the confidence interval 24.3 +- 1.2 the quantity 1.2 is called the _

Margin of error

Confidence interval

Mean +- margin of error

When the number of degrees of freedom is large, the student's t distribution is close to _ distribution.

Normal

Standard error

O/square root n

A single number that estimates the value of an unknown parameter is called a _ estimate

Point

If p^ is the sample proportion and n is the sample size, then square root p^ (1-p^) over n is the _

Standard error

If we estimate the necessary sample size and no value for p^ is available, the estimated sample size will be larger than if a value for p^ were available.

True

Increasing the sample size while keeping the confidence level the same will result in a narrower confidence interval

True

The confidence level is the proportion of all possible samples for which the confidence interval will cover the true values

True

The student's t distribution should not be used to find a confidence interval for u if outliers are presented in a small sample.

True

Point estimate

X-, s, s^2, p^

Critical value

Za/2

Margin of error

Za/2* O/ square root n