Question 1

In the statistical approach to determining sample size,the precision level is specified in the end.

Accepted Answer

In the statistical approach to determining sample size, the precision level (also known as the margin of error) is specified at the beginning of the study design process, not at the end. This helps in determining the required sample size to achieve the desired precision for the study's estimates.

Question 2

The statistical approach to determining sample size is based on the construction of confidence intervals around sample means or proportions.

Accepted Answer

The statistical approach to determining sample size relies on constructing confidence intervals around sample means or proportions in order to estimate the population parameters with a certain level of confidence.

Question 3

The process of generalizing the sample results to the population results is called statistical inference.

Accepted Answer

This is the definition of statistical inference.

Question 4

When determining the sample size,if the population standard deviation,σ is unknown and an estimate is used,the standard deviation should be re-estimated once the sample has been drawn.Next a revised confidence interval should be calculated to determine the precision level actually obtained.

Accepted Answer

This statement is true. When the population standard deviation is unknown and an estimate is used, the sample standard deviation is often used as an estimate. However, once the sample has been drawn and the sample standard deviation is calculated, it's important to use that value to re-estimate the population standard deviation. Then a revised confidence interval can be calculated to determine the actual level of precision obtained in the sample.

Question 5

Creative Research Systems (www.surveysystem.com)is a Web sites on the Internet that offer free use of sample size and/or confidence interval calculator.

Accepted Answer

The statement is true as Creative Research Systems provides free use of sample size and confidence interval calculators on their website for users.

Question 6

The sampling distribution of the mean is a binomial distribution.

Accepted Answer

The sampling distribution of the mean is not a binomial distribution. It is a normal distribution or a t-distribution, depending on the sample size and the population standard deviation.

Question 7

Assuming no measurement error,the reliability of an estimate of a population parameter can be assessed in terms of its standard error.

Accepted Answer

True. The standard error of an estimate measures the variability of the estimate due to sampling error. A smaller standard error indicates a more precise estimate and therefore higher reliability.

Question 8

The statistically determined sample size is the net or final sample size,the sample remaining after eliminating potential respondents who do not qualify or who do not complete the interview.

Accepted Answer

The statement is true. The statistically determined sample size is the final sample size after eliminating potential respondents who do not qualify or who do not complete the interview.

Question 9

The concept of a sampling distribution enables us to use probability theory to make inferences about the population values.

Accepted Answer

The concept of sampling distribution allows us to use probability theory to make inferences about population values.

Question 10

When the sample size is 10 percent or more of the population size,the standard error formulas will overestimate the standard deviation of the population mean or proportion.Hence,these should be adjusted by a finite population correction factor.

Accepted Answer

When the sample size is large enough (10 percent or more of the population size), the standard error formulas will overestimate the standard deviation of the population mean or proportion because the sample size is no longer considered small enough to be considered a random sample. This requires the use of a finite population correction factor to adjust the standard error formula.

Question 11

If the researcher is required to estimate several parameters,not just one,the calculation of sample size in these cases should be based on a consideration of all the parameters that must be estimated.

Accepted Answer

When estimating multiple parameters, sample size calculation should take into account all the parameters that need to be estimated. Ignoring any of the parameters may lead to underpowered studies and inaccurate conclusions.

Question 12

The confidence level is the range into which the true population parameter will fall,assuming a given level of confidence.

Accepted Answer

The confidence level represents the probability that the confidence interval contains the true population parameter, not the range itself. The confidence interval is the actual range estimate.

Question 13

Two major nonresponse issues in sampling are improving response rates and adjusting for nonresponse.

Accepted Answer

Improving response rates and adjusting for nonresponse are indeed two major nonresponse issues in sampling.

Question 14

The sampling distribution is the probability of the values of a sampling statistic computed for each possible sample that could be drawn from the target population under a specified sampling plan.

Accepted Answer

The answer of The sampling distribution is the probability of...

Question 15

When using the confidence interval approach to sample size determination,if the statistic of interest is a proportion,rather than a mean,the approach to sample size determination is very different.

Accepted Answer

The approach to sample size determination for a proportion involves a similar conceptual framework as for a mean, using a formula that accounts for the desired confidence level, the variability in the population (estimated by the proportion in the case of categorical data), and the margin of error. The formulas differ in their specifics (e.g., using the standard deviation for means vs. the standard error for proportions) but the underlying principles of determining how large a sample is needed to estimate the parameter of interest with a certain level of confidence and precision are consistent across both types of statistics.

Question 16

The confidence level is the probability that a confidence interval will include the population parameter.

Accepted Answer

This statement correctly defines the confidence level.

Question 17

When using the confidence interval approach to sample size determination,in some cases,precision is specified in relative rather than absolute terms.In other words,it may be specified that the estimate be within plus or minus R percentage points of the mean.

Accepted Answer

This is true. When using the confidence interval approach, precision can be specified in relative terms such as percentage points.

Question 18

Specify the level of confidence is the first step in the confidence interval approach to determining sample size.

Accepted Answer

The first step in determining sample size for a confidence interval is to specify the desired margin of error, not the level of confidence.

Question 19

The z value for a point is the number of standard deviations a point is away from the mean.

Accepted Answer

The answer of The z value for a point is...

Question 20

The confidence interval approach to sample size determination is based on the construction of confidence intervals around the means or proportions using the standardized variate formula.

Accepted Answer

The answer of The confidence interval approach to sample size...

Quiz 12: Sampling: Final and Initial Sample Size Determination