Lecture+11+su10+_independent+samples+t-test_

# Lecture+11+su10+_independent+samples+t-test_ - Sociology...

This preview shows pages 1–6. Sign up to view the full content.

02/23/11 Soc 210 summer 2010 1 Sociology 210 Lecture 11: The t Test for Two Independent Samples

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
02/23/11 Soc 210 summer 2010 2 Motivation Most of the time we are interested in comparing means of two groups rather than comparing the mean of one group to some hypothesized value This is called a two-sample hypothesis test (vs. one-sample before) Many comparisons of two groups result from dividing a larger sample into subsamples according to classification on some variable (e.g., gender or race) If the overall sample was randomly selected, these subsamples constitute independent random samples of their corresponding subpopulations But because each subsample is smaller than the overall sample, their statistics will not be as precise in estimating the parameters of their respective subpopulations as the overall sample is at estimating the parameters of the overall population
02/23/11 Soc 210 summer 2010 3 Hypotheses for the Difference of Means Goal: evaluate mean difference between two populations, μ 1 μ 2 , based on samples from each of those populations Two-tailed test H a : μ 1 - μ 2 0, equivalently, H a : μ 1 μ 2 (the means of the two populations are not equal) H 0 : μ 1 μ 2 = 0, equivalently, H 0 : μ 1 = μ 2 (the means are equal, i.e. no difference)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
02/23/11 Soc 210 summer 2010 4 Hypotheses for the Difference of Means One-tailed test : H a : μ 1 - μ 2 < 0, equivalently, H a : μ 1 < μ 2 H a : μ 1 - μ 2 > 0, equivalently, H a : μ 1 > μ 2 (the mean of one population is greater than the mean of the other population) H 0 : μ 1 - μ 2 0, equivalently, H 0 : μ 1 μ 2 H 0 : μ 1 - μ 2 0, equivalently, H 0 : μ 1 μ 2 (the means are equal or different in the opposite direction of what is predicted by H a )
02/23/11 Soc 210 summer 2010 5

This preview has intentionally blurred sections. Sign up to view the full version.

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

{[ snackBarMessage ]}

### What students are saying

• 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.

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

• 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.

Dana University of Pennsylvania ‘17, Course Hero Intern

• 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.

Jill Tulane University ‘16, Course Hero Intern