confidence Flashcards
For any given confidence interval, the true population mean will always fall
inside the interval.
True or false?
false
Suppose you construct a confidence interval for the population mean.
Then, your point estimate – the sample mean – will ALWAYS fall inside the
confidence interval no matter what level of confidence you use.
True or false?
true
Suppose a confidence interval is constructed for the mean of some variable X
with a 95% level of confidence. Suppose the confidence interval is [50,100].
Which of the following is a valid interpretation of this confidence interval?
A) You are 95% confident that the sample mean of X is between 50 and 100
B) There is a 95% probability that the sample mean of X is between 50 and 100
C) You are 95% confident that the true population mean of X is between 50 and 100
D) There is a 95% probability that the true population mean of X is between 50 and 100
29
c
AD constructed a confidence interval from a sample mean of 65, a population
standard deviation of 6, 95% confidence level, and a sample size of 200.
His colleagues convince him to instead assume a population standard deviation
of 7. Which of the following will occur?
A) The sample standard deviation will increase
B) The margin of error will increase
C) The standard error of the mean will decrease
D) The sample mean will increase
B
In general, higher confidence levels provide _____.
A) wider confidence intervals
B) narrower confidence intervals
C) a smaller standard error
D) unbiased estimates
a
A researcher is not satisfied with a study’s confidence interval, and wants to do
another study to find a smaller confidence interval. What should they change to
ensure they find a smaller confidence interval?
A) They should increase their confidence level and increase their sample size.
B) They should increase their confidence level and decrease their sample size.
C) They should decrease their confidence level and increase their sample size.
D) They should decrease their confidence level and decrease their sample size
c
hich of the following will increase the width of a confidence interval?
A) Decrease the confidence level
B) Decrease the sample size
C) Decrease the margin of error
D) Increase the sample size
b
What is the standard formula for a confidence interval?
A) population mean ± Margin of error
B) point estimate ± Margin of error
C) Standard deviation ± Margin of error
D) point estimate ± population mean
B
Using a confidence interval:
A) We can determine exactly what the population mean is
B) Determine how confident we are in our regression results
C) The range of possible values for our population mean
D) We get a range of values for that we believe we can find the population means
for a given confidence level
d
Which of the following YOU SHOULD NOT DO when creating a confidence
interval?
A) Find the sample standard deviation
B) Ensure the sample is randomly selected
C) Select a sample to get us our desired result
D) Find the sample mean
b
As the sample size increases, the margin of error ___________.
a. increases
b. decreases
c. stays the same
d. None of the answers is correct
b
Suppose you construct a 95% confidence interval based on a sample of students’
height and find a confidence interval of (67.3, 70.2).
What is the point estimate for students’ average height?
a. 67.3
b. 70.2
c. 69.5
d. 68.75
d
