Which of the following is/are true about confidence intervals (choose one or more)
Group of answer choices
when we calculate a 95% confidence interval there is statistical significance
knowing the range of a parameter is more accurate than a point estimate
confidence interval of the mean = mean +/- a margin of error using a constant
confidence intervals are abbreviated CI
Flag question: Question 2
Question 21.25 pts
The constant used in calculating the 99% confidence interval in the proportion formula is:
Group of answer choices
1.645
1.96
3.54
2.576
Flag question: Question 3
Question 31.25 pts
If you use the Excel Data Analysis Tools to calculate the descriptive statistics and check the box “confidence level for mean” what do you do with this number to obtain the confidence interval? (choose one or more)
Group of answer choices
do nothing – this number is the conficence interval
use this value to calculate the lower and upper bound of the interval
add and subtract this value from the median
add and subtract this value to the mean
Flag question: Question 4
Question 41.25 pts
Why do we need confidence intervals? (choose one or more)
Group of answer choices
To express statistical uncertainty
To accurately state a range of a population parameter
To give insight about the magnitude of the effect
To tell us the chance (95%) of a particular outcome
Flag question: Question 5
Question 51.25 pts
When calculating confidence intervals in this class the product of a constant times a margin of error is added and subtracted to what value to obtain the CI range?
Group of answer choices
median
standard deviation
alpha
mean
Flag question: Question 6
Question 61.25 pts
The average BMI for a sample of 10 preschoolers is 16.3, with a standard deviation of 1.4. What is the 90% confidence interval for the BMI of all preschoolers? (round to two decimal places)
Group of answer choices
(15.57, 17.03)
(15.29, 16.91)
(15.3, 17.3)
(15.49, 17.11)
Flag question: Question 7
Question 71.25 pts
When calculating the 99% confidence interval of the mean for a sample of 15 patients, what constant is used in the formula?
Group of answer choices
2.603
2.947
2.625
2.977
Flag question: Question 8
Question 81.25 pts
What affects the width of a confidence interval? (choose one or more)
Group of answer choices
Our desired confidence level.
Median of the sample
Sample size.
Variation within the population.
Flag question: Question 9
Question 91.25 pts
What is the constant used to calculate the 90% confidence interval of the mean when n=50?
Group of answer choices
2.576
1.645
1.96
Flag question: Question 10
Question 101.25 pts
If df=22, what constant do we use to calculate the 90% confidence interval of the mean?
Group of answer choices
1.321
1.717
1.714
1.323
Flag question: Question 11
Question 111.25 pts
If n=15, what constant do we use to calculate the 95% confidence interval of the mean?
Group of answer choices
1.762
2.132
2.145
1.753
Flag question: Question 12
Question 121.25 pts
As you increase your confidence level, what happens to the width of the confidence interval?
Group of answer choices
It stays the same.
It gets higher.
It gets narrower.
It gets wider.
Flag question: Question 13
Question 131.25 pts
When would you use the confidence interval formula for a proportion? (choose one or more)
Group of answer choices
You have summary information as a percentage or survey sample data
You do not know the standard deviation
Your sample size is under 30
To determine if the groups are significantly different
Flag question: Question 14
Question 141.25 pts
If in a sample of 355 adult males, we have a mean total cholesterol level of 185 mg, with s = 16. What is the 99% confidence interval for mean total cholesterol level of all males?
Group of answer choices
(183.6, 186.4)
(183.34, 186.66)
(181.45, 188.37)
(182.81, 187.19)
Flag question: Question 15
Question 151.25 pts
Which of the following is/are true about the Excel function = CONFIDENCE.NORM
Group of answer choices
This is the appropriate function to use to calculate CI of a proportion
This is the appropriate function to use if the sample size is greater than 30
This function uses the normal distribution (table B.1)
This is the appropriate function to use if the sample size is less than 30
Flag question: Question 16
Question 161.25 pts
For a sample with df = 5, what is the t-score constant to calculate a confidence level of 99%?
Group of answer choices
3.365
2.015
2.571
4.032
Flag question: Question 17
Question 171.25 pts
If n=20, what constant do we use to calculate the 99% confidence interval of the mean?
Group of answer choices
2.086
2.861
2.093
2.846
Flag question: Question 18
Question 181.25 pts
For a sample with df = 5, what is the t-score constant to calculate a confidence level of 95%?
Group of answer choices
1.943
2.571
1.476
2.015
Flag question: Question 19
Question 191.25 pts
Researchers find that the 95% confidence interval for women’s systolic blood pressure is (126.67, 127.93). How do you interpret this finding?
Group of answer choices
We are 95% confident that the true mean for women’s systolic blood pressure is between 126.67 and 127.93.
All of the above.
There is a 95% chance that the true mean for women’s systolic blood pressure is between 126.67 and 127.93.
95% of the data values for women’s systolic blood pressure are between 126.67 and 127.93.
Flag question: Question 20
Question 201.25 pts
In a randomly selected sample of 500 Phoenix residents, 445 supported mandatory sick leave for food handlers. Legislators want to be very confident that voters will support this issue before drafting a bill. What is the 99% confidence interval for the percentage of Phoenix residents who support mandatory sick leave for food handlers?
Group of answer choices
(86.7%, 91.3%)
(86.26%, 91.74%)
(85.4%, 92.6%)
There is not enough information to determine CI
