New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here


by: Claira Notetaker

Chapter6.pdf Q SCI 381

Claira Notetaker
GPA 3.5

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

week 6 of notes
Introduction to Probability and Statisitics
Patrick C, Tobin
Class Notes
QSCI, Stats and probability
25 ?




Popular in Introduction to Probability and Statisitics

Popular in Environmental Science

This 2 page Class Notes was uploaded by Claira Notetaker on Sunday February 14, 2016. The Class Notes belongs to Q SCI 381 at University of Washington taught by Patrick C, Tobin in Winter 2016. Since its upload, it has received 16 views. For similar materials see Introduction to Probability and Statisitics in Environmental Science at University of Washington.


Reviews for Chapter6.pdf


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 02/14/16
Chapter 6: Confidence intervals • Section 6.1, 6.2, 6.4 • Start using inferential statistics Confidence intervals • A range of values centered on a point estimate o Such as mean, variance, or SD • Denoted as a percentage or as a error rate = a (greek letter) o EX: § Level of confidence = 95% § A= .05 error rate Critical values • Denote observations that significantly differs from the expected distribution • Based upon the level of confidence used o Higher the level of confidence (lower a) the greater the critical value o Need the 2 tailed area Margin of error (E) • There are many sources of error in experiments o Random error, observational errors, environmental error o Some are unavoidable • Increase precisions, finding a sample size! o The n’s justify the means § n = (Z(c) x SD/ E)^2 ú Z(c) = level of confidence obtained from z score • In decimal form ú E = margin of error • E= Zc*(SD/n^1/2) ú SD = standard deviation o Higher background variation => sample size increase o Higher level of confidence => sample size increase o The lower the desired margin of error => sample size increases • Confidence interval o Point estimate – E < parameter < point estimate + E o EX: § Estimated mean – E < u , estimated mean + E Or § U = point estimate of the mean + or – E o –E = lower confidence interval o +E = upper confidence interval T-distribution • E = Tc*(SD/n^1/2) • Tc gives you both the level of confidence and the sample size Degree of freedom • The bigger the sample size, you have more wiggle room o SD estimation = one loss of degree of freedom Chi-squared distribution (X^2) • Calculating the confidence interval for the variance and the standard deviation o The confidence interval is based on a given level of confidence, degree of freedom, and the chi-squared distribution • Asymmetrical graphs o Have a bit of a long tail § Allows for a different level of variation • ((n-1)SD^2/X^2R)^1/2 < SD < ((n-1)SD^2/X^2L) o X^2R = right tail (5% above wanted Level of confidence) o X^2L = left tail (5% bellow wanted level of confidence) o N-1 because we estimated the SD (one less DoF) • 77.929 = .26 • 124.342 = .17 • 3.5 <4.4< 5.6


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Kyle Maynard Purdue

"When you're taking detailed notes and trying to help everyone else out in the class, it really helps you learn and understand the I made $280 on my first study guide!"

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.