Class Notes (807,637)
Canada (492,763)
SOAN 3120 (35)
Lecture 5

quant week 5.docx

3 Pages
Unlock Document

University of Guelph
Sociology and Anthropology
SOAN 3120
Scott Schau

Quantitative Methods Week 5 SOAN 3120 Oct. 9, 11 Confidence Interval - A level C confidence interval for a parameter has two parts: an interval calculated from the data, usually of the form: estimate ± margin of error - A confidence level C, which gives the probability that the interval will capture the true parameter value(μ) in repeated samples, or the success rate for the method Interpreting a confidence interval for a mean - A confidence level can be expresses as Xbar ±m (m is the margin of error) - Two endpoints of an interval μ possibly within (xbar – m) to (xbar + m) - Confidence intervals contain the population mean μ in C% of samples. Different areas under the curve give different levels C. Practical use of z: z* - Z* is related to the chosen confidence level C - C is the area under the standard normal curve between –z* and z* - The confidence interval is thus : xbar ± z* ơ/ √n Link between confidence level and margin of error - The confidence level C determines the value of z* (in table C). the margin of error also depends on z*. higher confidence C implies a larger margin f error m, thus less precision in our estimates) - A lower confidence level C produces a smaller margin of error m, thus better precision in our estimates Impact of sample size - Spread in the sampling dist, of the mean is a function od the number of individuals per sample. - The larger the sample size the smaller the SD(spread) of the sample mean dist, - But the spread only decreases at a rate equal to √n Sample size and experimental design - You may need a certain margin of error (eg. Drug trial manufacturing specs). In many cases, the population variability (ơ) is fixed, but we can choose the number of measurements (n). - So plan ahead what sample size to use to achieve that margin of error - M= z* ơ/ √n  n= (z*ơ/m)² The reasoning of tests of significance - Suppose a basketball player claimed to be an 80% free throw shooter. To test his claim, we have him attempt 50 free throws. He makes 32 of them. His sample proportion of made shots is 32/50 = .64 what can we conclude about the claim based in this sample data? Quantitative Methods
More Less

Related notes for SOAN 3120

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.