Unit 10 Confidence Intervals Flashcards
What is the parameter for a 1 sample t interval for means?
What is the statistic for a 1 sample t interval for means?
x-bar
What is the parameter for a 1 proportion z interval?
p
What is the statistic for a 1 proportion z interval?
p-hat
What is the statistic for a 2 sample t interval for means?
What is the statistic for a 2 proportion z interval?
What are the 3 conditions for a confidence interval for proportions?
- We have a random sample.
- The population is greater than 10n.
- The sampling distribution is approx. normal because np-hat and nq-hat >10.
What are the 3 conditions for a confidence interval for means?
- We have a random sample.
- The population is greater than 10n.
- The sampling distribution is approx. normal because n > 30 OR the original population is approx. normal.
What are the 4 steps to create a confidence interval?
Don’t Cry, Cry, Cry
- Define Parameter (& Name your interval)
- Check Conditions
- Calculations
- Conclusion
What are 2 ways to decrease the width of a confidence interval?
- Decrease the confidence level (decrease critical value) 2. Increase sample size, n.
What is the standard error of p-hat?
What is the standard error of x-bar?
Standard error is another name for _________.
Standard Deviation
The 90% confidence level for the mean number of pencils a teacher has is (5, 85). Interpret the confidence level.
90% of the intervals constructed in this way will contain the true mean number of pencils a teacher has.
The 90% confidence level for the mean number of pencils a teacher has is (5, 85). Interpret the confidence interval.
We are 90% confident that the true mean number of pencils a teacher has is between 5 and 85.