...Stat 141 R1 - Lecture #35 Announcements: 1) Assignment #11 Question 5: The answer is wrong … should be “fail to reject” but MyStatLab wants “reject”... so give the wrong answer for full marks in this question 2) Exam: STAT 141 R1 3 hrs 1400 Wed Apr 17 MAIN GYM, ~45 Multiple Choice Questions Chapters 7, 8, 18-28 …. some pre MT skills will be required. Simple Linear Regression …. continued Last time: Ex) Predicting final exam marks (%) from midterm exam marks (%) in a class of 88 students: Student | #1 | #2 | … | #88 | Midterm mark | 67% | 72% | … | 88% | Final mark | 62% | 50% | … | 91% | Stat 141 R1 - Lecture #35 page 2 Given x = midterm percentage, y = final percentage, n=88, x = 67.812, y = 52.643, sx = 17.922, sy = 25.430, r = 0.718 ∑(yi–ŷi)2 = 27278.82 We had calculated: The slope and intercept of the sample line of best fit: * sample line of best fit: y= -16.443 + 1.019 x An estimate for σ (standard deviation about the population line): se Given SSE = ∑(yi–ŷi)2 = 27278.82 : se2=SSEn-2=27278.8288-2=317.196 →σ≈se=317.196=17.810 Stat 141 R1 - Lecture #35 page 3 Inference for the population slope β1 When the 4 basic assumptions of the SLR model are satisfied: o The relationship between x and y is sufficiently linear. Presuming linearity, this means, at any x, με = 0. o The std. dev. of ε is the same for any particular x (constant). o The...
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...1. Advantages and Disadvantages of Public TransportNowadays, many kinds of public transport can be seen on the road, even though people drive their own car. It is usually on time and economical. Firstly, one of the advantages is that using public transport is very economical. Taking buses and trains is cheaper than using private cars. If people have their own car, they have to pay a lot of money for service, repairs, and insurance. It maybe will cost all the money people earn. Moreover, there are many discounts for some individuals, like students, old people, and children. They can get cheaper prices by taking public transport. Students have to go to school almost every day, and they usually take public transport to school and home. It is more economical for students. In addition, a further advantage is that using public transport can preserve the environment. It can reduce pollution, because there are less cars driving on the road, and there are fewer fumes and also less traffic jams. Furthermore, it can increase the spaces in the city, because there are less cars parking. Taking buses and trains is able to keep the environment green, However, one of the disadvantages is that using public transport is inconvenient. It can be crowded. For instance, there are always too many individuals on the same bus in rush hour. Maybe thieves are on the bus they take. The public transport does not operate 24 hours a day. People have to follow the time table, so they must wait for it. Furthermore...
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