As sample size goes up, what tends to happen to 95% confidence intervals?

• A) They become more precise
• B) They become more narrow
• C) They become more precise and narrow
• D) They become wider

Which of the following is the most common example of a situation for which the main parameter of
interest is a population proportion?

• A) An observational study
• B) A normal experimen
• C) A binomial experiment
• D) A randomized experiment

What condition is required before the central limit theorem justifies approximating the sampling distribution of the mean with a normal distribution?

• A) 20n < N
• B) n(1 - p) > 5
• C) n > 30
• D) n < 30

In sampling from a large population with sigma= 12, the standard error of the mean is found to be 3. The size of the sample used is:

• A) 16
• B) 22
• C) 12
• D) 11

An estimator is always a:

• A) Statistic and Random variable
• B) Random variable
• C) Statistic
• D) Parameter

In the method of moments, how many equations are required for finding two unknown population parameters?

• A) 2
• B) 1
• C) 4
• D) 3

In sampling from a large population with б = 45. The size of the sample used is 12, the value of the standard error will be:

• A) 3.66
• B) 1.2
• C) 5.9
• D) 12.99

Consistency is a ....... property.

• A) Non-random sample
• B) Unique sample
• C) Small sample
• D) Large sample

As the sample size _____________ the variation of the sampling distribution of the same means ______________:

• A) Increases, remains the same
• B) Decreases, remains the same
• C) Decreases, decreases
• D) Increases, decreases

In sampling from a large population with sigma = 20, the standard error of the mean is found to be 2. The size of the sample used is:

• A) 40
• B) 100
• C) 10
• D) 20

If we have two normally distributed populations then sampling distribution of the difference of sample means will be:

• A) t-distribution
• B) Chi-square distribution
• C) Normal distribution
• D) F-distribution

An estimator is said to be.......... if its expected value is equal to true value of its parameter.

• A) Unbiased
• B) Efficient
• C) Consistant
• D) Biased

As a rule of thumb, when n>=30, then we can assume that………is normally distributed:

• A) Probability distribution
• B) Sampling distribution of sample mean
• C) Sampling distribution
• D) Binomial distribution

Assume a large distribution in which б = 6. What is the standard error of the mean based on samples for which n = l0?

• A) 1.9
• B) 3
• C) 15
• D) l67

The Central Limit Theorem states that if a sample size n is sufficiently large (say, at least 30), then:

• A) The population mean and sample mean are equal
• B) The sampling distribution of sample mean is exactly normal
• C) The sampling distribution of sample mean is approximately normal
• D) The sampling distribution of the population mean is approximately normal

In sampling from a large population with б = 35, the standard error of the mean is found to be 4. The size of the sample used is:

• A) 25
• B) 56
• C) 77
• D) 15

Sampling distributions are:

• A) The probability distribution that is assigned to population parameters
• B) Refers to the margine of error
• C) The probability distribution of sample statistic
• D) None of above

P 0 1/3 2/3 1
f(p) 1/20 9/20 9/20 1/20
The mean of the sampling proportion will be:

• A) 9/20
• B) 10/20
• C) 11/20
• D) 12/20

$${\text{The mean of the sampling distribution of }}\overline x _1 - \overline x _2 {\text{, denoted by }}\mu _{\overline x _1 - \overline x _2 } {\text{is equal to the difference between repective}}$$

• A) Population Means
• B) Sample Means
• C) Sample Proportions
• D) Population Proportions

The width of the confidence interval is called______ of the estimate.

• A) Accuracy
• B) Biased
• C) Precision
• D) Unbiasedness