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VOCAB!!!
Confidence Intervals!!!
Finding the Sample Size!!!!
Finding the Margin of Error!!
100
What is a single value estimate for a population parameter?
Point estimate
100
A random sample of 30 households was selected as part of a study on electricity usage, and the number of kilowatt-hours was recorded for each household in the sample for the March quarter of 2006. The average usage was found to be 375kWh. In a very large study in the March quarter of the previous year it was found that the standard deviation of the usage was 81kWh. Assuiming the standard deviation is unchanged and that the usage is normally distributed, create a confidence interval for a 99% confidence level for the mean usage in the March quarter of 2006?
I am 99% confident that the true average number of kilowatt-hours for households in March of 2006 is between 336.92kWh and 413.08kWh.
100
C=0.90, S=6.8, E=1
125.13
100
A company has credit rating scores of a simple random sample of applicants for credit cards: 95% confidence, n=50, mean=677, and standard deviation is known to be 68.
18.85
200
What is an interval or range of values used to estimate a population parameter?
Confidence interval.
200
An industrial designer wants to determine the average amount of time it takes an adult to assemble an "easy to assemble" toy. A sample of 16 times yielded an average time of 19.92 minutes, with a sample standard deviation of 5.73 minutes. Normally distributed, provide a 95% confidence interval for the mean assembly time.
I am 95% confident that the true average amount of time it takes an adult to assemble an "easy to assemble" toy is between 17.11 minutes and 22.73 minutes.
200
C=0.95, S= 2.5, E=1
24.01
200
The breaking distance of a simple random sample of cars: 95% confidence; n=32, mean=137 ft, and standard deviation is known to be 7ft.
2.43
300
What is a Level of Confidence?
What is the probability that the interval estimate contains the population parameter.
300
The recommended retail price of a brand of designer jeans is $150. The price of the jeans in a sample of 16 retailers is on average $141, with a sample standard deviation of $4. The prices can be assumed to be normally distributed. Construct a 95% confidence interval for the average sale price.
I am 95% confident that the true average retail price of a brand of designer jeans is between $139.04 and $142.96.
300
c=0.80, s=4.1, E=2
6.91
300
C=0.95, s=2.3, n=49
E= 0.644
400
What is the greatest possible distance between the point estimate and the value of the parameter it is estimating?
Margin of Error
400
The distribution we use whenever we use sample standard deviations to estimate population mean.
What is the t distribution.
400
c=0.98, s=10.1, E=2
137.98
400
The shape of the sampling distribution of p(hat) when the sample is large (i.e., np ≥ 10 and n(1 – p)≥ 10) and random.
What is approximately normal
500
What is the number of free choices left after a sample statistic is calculated?
Degrees of freedom
500
The value that determines the spread of a t distribution.
What are degrees of freedom
500
The checks you need to make when performing a one-sample t procedure— confidence interval for µ.
What are data collection (SRS) and plot has no extreme skewness or outliers.
500
If the probability calculations involved in an inference procedure remain fairly accurate when a condition for using the procedure is violated
Robust procedure.