During Unit 8,you will learn about how to use a sample statistic (such as a samplemean) to estimate the value of a population parameter (such as the truepopulation mean). For example, you can estimate the true mean weight ofall newborn babies in the entire world by collecting a sample. Becausethe sample is only a small portion of the entire population, errors willhave to be considered. Using a sample to create a range or interval ofvalues that estimates a population value is called a “confidenceinterval.” The formula for calculating a 95% confidence interval for a population mean is: Confidence Interval for Population Mean: sample mean – E < population mean < sample mean + EError “E” = (1.96)*(s) / sqrt(n) “s” is the standard deviation and “n” is the sample size. Part 1: Confidence Intervals Whyis it often impossible to know the actual value of any populationparameter? Give an example of a population parameter that you cannotcalculate, but that you can estimate. A sample can be used toestimate a population parameter. How does the sample size affect theestimate? If the sample is larger, what will this do to the error E? Usethe Confidence Interval formula above and calculate the 95% confidenceinterval for any population mean of your choice. Write down (invent) thesample size (be sure it is 30 or above), the sample mean, and thesample standard deviation. Then, calculate the confidence interval.Remember, you are inventing all the values, so no two posts should lookthe same. Use Excel and your invented values to calculate theconfidence interval. Include and compare the results. (Tutorials can befound in Doc Sharing). Again, remember that your sample size must be 30or above.
