1 / 9

Determining the Appropriate Sample Size

Determining the Appropriate Sample Size. SAMPLE SIZE REQUIREMENT - ESTIMATING  WITH  KNOWN where: z = Critical value for the specified confidence interval e = Desired margin of error  = Population standard deviation. Pilot Samples.

hinds
Download Presentation

Determining the Appropriate Sample Size

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Determining the Appropriate Sample Size SAMPLE SIZE REQUIREMENT - ESTIMATING  WITH  KNOWN where: z = Critical value for the specified confidence interval e = Desired margin of error  = Population standard deviation

  2. Pilot Samples A pilot sample is a smaller sample taken from the population that is used to provide an estimate for the population standard deviation.

  3. Example of Determining Required Sample Size(Example 7-7) The manager of the Georgia Timber Mill wishes to construct a 90% confidence interval with a margin of error of 0.50 inches in estimating the mean diameter of logs. A pilot sample of 100 logs yield a sample standard deviation of 4.8 inches.

  4. Estimating A Population Proportion SAMPLE PROPORTION where: x = Number of occurrences n = Sample size

  5. Estimating a Population Proportion STANDARD ERROR FOR p where:  =Population proportion n = Sample size

  6. Confidence Interval Estimates for Proportions CONFIDENCE INTERVAL FOR  where: p = Sample proportion n = Sample size z = Critical value from the standard normal distribution

  7. Example of Confidence Interval for Proportion(Example 7-8) 62 out of a sample of 100 individuals who were surveyed by Quick-Lube returned within one month to have their oil changed. To find a 90% confidence interval for the true proportion of customers who actually returned: 0.70 0.54

  8. Determining the Required Sample Size MARGIN OF ERROR FOR ESTIMATING where:  = Population proportion z = Critical values from standard normal distribution n = Sample size

  9. Determining the Required Sample Size SAMPLE SIZE FOR ESTIMATING where:  = Value used to represent the population proportion e = Desired margin of error z = Critical value from the standard normal table

More Related