One goal of stratified sampling plans is to decrease the amount of variability in each stratum. This ...

One goal of stratified sampling plans is to decrease the amount of variability in each stratum. This can be accomplished by
 a. making the strata internally heterogeneous.
  b. increasing the amount of sampling error.
  c. decreasing the magnitude of the overall sample mean.
  d. making the strata internally homogeneous.
  e. using a 99 confidence level instead of a 95 confidence level.

Question 2

The standard error of the estimate of the statistic in question
 a. is equal to the square of the variance of the estimate.
  b. measures the variability that exists between strata.
  c. corresponds to the population mean.
  d. is used when comparing statistical efficiency.
  e. cannot be calculated from a stratified sample.

Question 3

The differences between a cluster sample and a stratified sample are in a
 a. cluster sample, the parent population is divided into mutually exclusive and exhaustive subsets.
  b. stratified sample, the parent population is divided into mutually exclusive and exhaustive subsets.
  c. stratified sample, a simple random sample of elements is chosen independently from each group or subset, while in a cluster sample, a random sample of the subsets is selected.
  d. cluster sample, a simple random sample of elements is chosen independently from each group or subset, while in a stratified sample, a random sample of the subsets is selected.
  e. None of the above.

Question 4

In a stratified sample with five strata, each comprising 1/5 of the population, the sample mean for each stratum will receive what weight when calculating the overall sample mean?
 a. 1.20
  b. 0.20
  c. 0.15
  d. 1.00
  e. Cannot be determined with information given in the question.

Question 5

The essential difference between a confidence interval constructed employing a stratified sample and that constructed employing a simple random sample is that with the stratified sample
 a. a point estimate of the population mean is not required.
  b. determination of the estimate of the mean and standard error of estimate involves the use of weights.
  c. the strata results are appropriately weighted by a method of curvilinear estimation.
  d. inferences are drawn on the basis of the known population mean and variance.
  e. the researcher does not need to specify the degree of confidence.

Question 6

Which of the following is TRUE?
 a. When sampling from a population that is highly skewed, a cluster sample generally provides the most representative sample.
  b. Stratified sampling is a very useful sampling technique. It allows closer examination of the characteristics of particular subgroups. It also lowers the chance of error by ensuring that subgroups are adequately represented in the sample. However, this method generally produces less precise estimates of population values than simple random samples.
  c. In calculating the standard error of the mean when using a stratified sample, one finds that differences among strata means do not enter the estimate.
  d. When using proportional allocation in stratified random sampling, one samples from each of the strata in proportion to their respective variabilities.
  e. The sampling distribution of means for stratified sampling is generally less concentrated than that obtained from simple random sampling.

Question 7

The interesting thing about confidence intervals established employing stratified sampling is that
 a. The within-strata variability does not enter into the calculation of the standard error of estimate.
  b. The between-strata variability does not enter into the calculation of the standard error of estimate.
  c. Neither the within-strata variability nor the between-strata variability enters into the calculation of the standard error of estimate.
  d. The confidence interval is wider than that established employing simple random sampling.
  e. The sample mean provides a biased estimate of the population mean.

Question 8

Under which of the following conditions can the population mean be estimated without error employing a stratified sample?
 a. When the population is partitioned so that the number of elements in each stratum is proportional to size of the sample to be taken from each stratum.
  b. When the population is partitioned so that the elements in each stratum are equal.
  c. When the population is partitioned in such a way that the variances within strata are equal.
  d. When the population is partitioned so that the elements in each stratum are normally distributed.
  e. None of the above.

Question 9

A researcher wishes to sample from a population in which two important segments make up less than 2 of the population, but wishes to develop confidence intervals describing their behaviors. Which type of sampling is most appropriate?
 a. Stratified sampling
  b. Convenience sampling
  c. Systematic sampling
  d. Simple random sampling
  e. Judgment sampling