SOC 3811 Basic Social Statistics

1. SOC 3811 Basic Social Statistics

2. Reminder • Hand in your Assignment 4

3. Class overviewCompare means of two groups • Dummy variable regression model • Two sample t-test • Group exercise

4. Dummy Regression Model • Do men and women have different wages? • Ho: = 0 Ha: ≠ 0 • For males: Female=0, so the average male wages = • For females: Female=1, so the average female wages= • The difference between the means of male and females =

5. If -1.96<Z*<1.96 or Sig. (p value)>.05 → can’t reject the null hypothesis The dummy variable has no influence. The means for two groups are the same • If ｜Z*｜≥ 1.96 or Sig. (p value)≤.05 → reject the null hypothesis The dummy variable does have an influence. The means for two groups are different.

6. Sampling distribution of differences in means T-test • Sampling distribution: the distribution of all possible estimates of the difference in means

7. T-test • How likely is it to draw means with a difference of , if the difference in population means is really 0? • If common, we can’t conclude anything • If rare, we can conclude that the population means differ.

8. T-test • Ho: Ha: • For males: the average male wages = • For females: the average female wages= • The difference between the means of male and females= =

9. Calculating z/t : For any two means, the difference will also fall in a certain range. We can guess the range in which it typically falls one-tail test two-tail test a=.05 a/2=.025 a/2=.025 -1.645 -1.96 1.96

10. If -1.96<Z*<1.96 or Sig. (p value)>.05 → can’t reject the null hypothesis The means for two groups are the same. • If ｜Z*｜≥ 1.96 or Sig. (p value)≤.05 → reject the null hypothesis The means for two groups are different.

11. Dummy variable regression model

12. T- test

15. Dummy Regression model

16. T-test