Cal Poly, STAT 301
Excerpt: ... STAT 301 Exam 2 Preparation Logistics: Wed Feb 18 from 10:10-11am Open-book, open-notes Bring calculator No computer use Material from Tues Jan 27 Fri Feb 13, HW9-14 Optional review problems o Ch1: 20, 21, 23, 24, 26, 43, 44, 46, 47, 51 o Ch5: 1, 3, 5, 8, 10, 13, 16, 17, 20, 22 Overview: We have analyzed studies that involve two categorical variable, for which the results can be organized in a two-way table. We have studied how to conduct inferences depending on whether the data were collected from: A randomized experiment Independent random samples Neither We have also considered how the scope of conclusions to be drawn depends on how the data were collected. More specifically, random assignment allows for drawing cause/effect conclusions, and random sampling allows for generalizing to a larger population. We learned three ways to conduct statistical inference in this situation: Simulation o Randomization model (for randomized experiment) o Binomial sampling mode ...
University of Florida, STA 4322
Excerpt: ... dispensing machine is said to be out of control if the variance of the contents exceeeds 1.15 (the unit of volume is deciliter). If a random sample of 25 drinks from this machine has a variance of 2.03, does this indicate at the 0.05 level of significance that the machine is out of control? Assume that the contents are approximately normally distributed. What can you say about the p-value of this test? 4. Two groups of elementary school children were taught to read by using different methods. The number of students in each group was 50. At the conclusion of the instructional period, a reading test yielded the results y1 = 74, y2 = 71, and s1 = 9, and s2 = 10. (a) Is there a difference between the population means for the two groups at the = 0.05 level? Please state what case is relevant here. (b) What is the p-value for this test? 5. A psychological study was conducted to compare the reaction times for men and women to a stimulus. Independent random samples of 50 men and 50 women were employed in the ex ...
UIllinois, STAT 400
Excerpt: ... Statistics 400 Section 7.3 Confidence Intervals for Difference of Two Means If X1, X2, ., Xn are observations of a random sample of size n from a normal distribution N( x, 2 x ), then we have X is N( x, 2 x /n) If Y1, Y2, ., Ym are observations of ...
University of Texas, ECON 329
Excerpt: ... Practice Questions 6 1. C 2. B 3. D 4. C 5. B 6. B 7. D 8. C 9. B 10. A 11. D 12. B 13. C 14. C 15. A 16. A 17. D 18. B 19. B 20. C 21. D 22. X tn 1 , / 2 s / n = 63.57 2.032(17.32) / 5.92 = 63.57 Then, UCL = 69.52 and LCL = 57.62. 35 = 63.57 5.95. 23. If independent random samples of size 35 are repeatedly selected from the population and 95% confidence intervals for each of these samples are determined, then over a very large number of repeated trials, 95% of these intervals will contain the value of the true average amount of money a typical college student spends per day during spring break. 24. E ( X ) [ E ( X 1 ) E ( X 2 )] / 2 ( ) / 2 E (Y ) [ E ( X 1 ) 3E ( X 2 )] / 4 ( 3 ) / 4 E ( Z ) [ E ( X 1 ) 2 E ( X 2 )] / 3 ( 2 ) / 3 Since E ( X ) E (Y ) E ( Z ) , then all three estimators are unbiased. 25. Var ( X ) [Var ( X1 ) Var ( X 2 )]/ 4 ( 2 2 ) / 4 2 / 2 Var (Y ) [Var ( X1 ) 9Var ( X 2 )]/16 ( 2 9 2 ) /16 5 2 / 8 Var (Z ) [Var ( X1 ) 4Var ( X ...
The University of Oklahoma, ECON 2843
Excerpt: ... ECON 2843 Problem Set 8 1. Problem 9.6 in Newbold on p. 323. A company which receives shipments of batteries tests a random sample of nine of them before agreeing to take a shipment. The company is concerned that the true mean lifetime for all batter ...