Exam 16: Determining Sample Size

Exhibit 16.3 Stella would like to determine the amount of the average purchase at her software store with a total precision of $10,a historical average purchase variance of $150,and at a 95% confidence level. Refer to Exhibit 16.3.If Stella wishes to increase the total precision to $5,what sample size is needed?

There is a trade-off between the confidence level and the degree of precision of the estimate when the

A researcher has estimated that she needs a sample of size n=100 from a population consisting of 1,000 elements.Recognizing that the sample represents 10% of the population,she decides to apply the finite population correction factor to her initial estimate.What is the corrected sample size?

Exhibit 16.5 A researcher wished to estimate the proportion of all families who go to the movies at least once a month.He wished the estimate to be accurate within plus or minus 4 percentage points and further desired a 95 percent confidence interval (z = 2)around the result.Additionally,he estimates the population proportion as 0.30. Refer to Exhibit 16.5.The required sample size is

Exhibit 16.4 A researcher is attempting to determine the average annual expenditures per household on compact discs.Suppose $600 was considered the upper limit and $0 the lower limit.There are no past studies on which to base an estimate of s. Refer to Exhibit 16.4.If the desired precision is +$25 and the desired confidence interval is 95%,what is the necessary sample size?

If a researcher wishes to increase the confidence level from 95% to 99%,what approximately will be the effect on sample size?

Sample size depends upon the

Which of the following is(are)a valid reason(s)why a researcher might not want to increase the precision of the estimate?

Toppen Olaf Olson,plant manager at the Ridgway Tanning Factory,was interested in the average number of hides currently sold each day at the plant.The daily variance of hides sold at the plant last year was 132.Olaf would like to be 90 percent confident (z = 1.645)in his results and be within a daily range of +/- 5 hides.Olaf needs a sample of what size to achieve his desired level of precision and confidence?

Discuss three factors researchers must take into consideration when determining sample size.

People who have looked online for health information are called "____________________."

Two standard deviations about the mean of a normal distribution include approximately ____ of all observations.

is the

The error associated with the estimation of a population parameter from a sample statistic is

Sample size (n)is related to the degree of the confidence (1-alpha)in that the

Which of the following statements is most accurate regarding the relationship between sample size and the sample representativeness?

The degree of error in a study,or the size of the estimating interval is called ____________________.

Exhibit 16.4 A researcher is attempting to determine the average annual expenditures per household on compact discs.Suppose $600 was considered the upper limit and $0 the lower limit.There are no past studies on which to base an estimate of s. Refer to Exhibit 16.4.What is your best estimate of the standard deviation?

When estimating a population proportion instead of a mean,in order to determine the sample size necessary you need all of the following information EXCEPT

The finite population correction factor is used when