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