Statistical Inference and Interval Estimate Essay

1251 WordsMay 30, 20136 Pages
Submit completed tests as word or pdf files via email to paul.kurose@seattlecolleges.edu Due: Sunday, May 19 (by 8am). 1. a) In Chapter 6, you learned to find interval estimates for two population parameters, a population mean and a population proportion. Explain the meaning of an interval estimate of a population parameter. An interval estimate for a specified population parameter (such as a mean or proportion) is a range of values in which the parameter is estimated to lie. In Chapter 6, you were assigned to find interval estimates for a population mean and a population proportion. b) Is finding an interval estimate an example of inferential or descriptive statistics? Explain. It is an interval estimate is an example of…show more content…
Explain your reasoning. The confidence level will increase the margin of error of a Confidence-interval estimate. d) If confidence level is kept constant, what effect will an increase in sample size have on the margin of error of a confidence interval estimate? Explain your reasoning. An increase in sample size will decrease the margin of error of a Confidence-interval estimate. 3. a) A simple random sample of thirty-six students has a mean age equal to 25 years. Given =4.8 years, determine a 90% confidence interval estimate for µ. E ≤0.8, µ = 25 so The 90% confidence interval is 25 ± 1.32 = 23.68 and 26.32 b) Determine the sample size required to have a (smaller) margin of error of 0.8 years for a (higher) 95% confidence level for the confidence interval estimate for µ in part a) above. The sample size should be n ≥ 138.3 ≈ 139 for a 95% confidence level 4. A) In a simple random sample of students from colleges across the state of Washington, 490 are in favor decreasing the size of their college administration and 310 are not. Determine a 95% confidence interval estimate for the proportion of Washington college students who favor decreasing the size of their college administration. With a 95% confidence, I can say the proportion of Washington college students who favor decreasing the size of their college administration