Stat 217 – Lecture 16

Stat 217 – Lecture 16 Review Final note of caution: Research shows 14% of statistics are made up on the spot

Announcements • Presentations tonight and tomorrow • 5:30-6:30 tonight • 6:00-7:00 tonight • 6:00-7:00 tomorrow night • Project group evaluation form

Last Time – Two Quantitative Variables • Numerical and graphical summaries • Scatterplot (response vs. explanatory) • Direction, strength, linear • Outliers and influential observations • Correlation coefficient, r • Measures strength and direction of linear relationship • Model: Least square regression line

Last Time – Two Quantitative Variables • H0: The two variables are not related • Ha: The two variables are related • Positive relationship (b>0) • Negative relationship (b<0) • Can assume technical conditions are met • Test statistic: t • If p-value is small, have evidence that the association observed in sample is stronger than would expect “by chance”

Final Exam • 9:10-11:00 or 11:10-1:00 (110 min) • Tables, Description of procedures will be provided • Review Handout • Review Session • Review Projects • Office hours, email

Comments on HW 6 • Defining parameters • Let p = proportion who use cocaine • Let p = proportion who said they used • Let p = proportion who would say they use if asked via phone • Insignificant results • Our p-value is large so we can’t make a conclusion

Comments on HW 6 • Interpreting confidence intervals • We are 95% confident that our results are in the interval • We are 95% confident that both p1 and p2 are in the interval • We are 95% confident that p1-p2 is in the interval • 95% of intervals constructed this way would capture p1-p2

Comments on HW 6 • One vs. two-sided p-values • p-value • probability of data like this • probability of a result/test statistic at least as extreme when Ho is true

Stat 217 – Lecture 16