Whatsamplesizeshouldbetakenassumethat

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: e determine the interval width first, and derive the required sample size. The phrase “estimate the mean to within e units”, translates to an interval estimate of the form s s x ±e Slide 17 Determining the Sample Size s The required sample size to estimate the mean is zα 2σ n= e s 2 The “e” is also known as the acceptable margin of error allowed. Slide 18 Determining the Sample Size s Example • To estimate the amount of lumber that can be harvested in a tract of land, the mean diameter of trees in the tract must be estimated to within one inch with 99% confidence. • What sample size should be taken? Assume that diameters are normally distributed with σ = 6 inches. Slide 19 Determining the Sample Size s Solution • The estimate accuracy is +/­1 inch. That is e = 1. • The confidence level 99% leads to α = .01, thus zα/2 = z.005 = 2.575. • We compute zα 2σ 2.575(6) 2 n= = = 239 1 e 2 If the standard deviation is really 6 inches, the interval resulting from the random...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern