Stats21_Purves_07F_Midterm1

Stats21_Purves_07F_Midterm1 - , (5) 1. The quotation below...

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Unformatted text preview: , (5) 1. The quotation below is taken from an article in the New York Times of April 18, 2006: g , In the Emerggncy-Room, Seat Belts Matter, Too or people who survive car ten, a co-author of the study and the wrecks, those who weren’t wearing ' chairman of emergency medicine ‘seat beltsvar'e three times .as likely at the Medical College of Wiscon- to die in an emergency room as ‘ sin. The research was led by Shane those who were, researchers say. Allen, a student there. The findings, which appear in the The study also found that victims current issue of Academic Emer— not wearing seat belts were more gency Medicine,"are based on a re- likely to suffer moderate to severe view of what happened to more injuries to the head, face, chest and "than 23,000 people in car wrecks in spine. Wisconsin in 2002. Those patients also cost about 25 Emergency room doctors treat— percent more to treat in the ER, ing the victims routinEIyAwant to but the expenses did not stop there. know if a patient was Wearing a Patients who had not worn seat seat belt, 50 they know What kind 0f belts were more than twice as like- mjuries to 100k for- 1y to need hospitalization as those . ‘iIf You’re n0t Wearing a seat belt. who had. Only about a'fifth were that’s an important Piece Of infor‘ discharged from the emergency Imatlon,” said Dr. Stephen Hargar' room, the study found. _ - I True or false, and explain. From the study (at least as described in the above quotation), it would be correct to conclude that almost all of the 25% higher costs incurred in the E. R. could have been avoided had the drivers (or passengers) treated there been wearing seat belts at the time of the accident. Wife» 5 l . ,r. ,, . l .i' l LY INU/ Karl's CLMa/ V44 07 L"”““"’ , -, lac “M r: a. farm-n = v * *” ‘ i ’ fl ’ r (4 f f 4/ {Iii-1‘)“ n' C" ‘1" I lizmfi/ \ .CV ‘30“ " ' an A )pd“ “3/ i L‘til ’4 (Jodi vmo if 092’ —fl(L(((¢55/E{fi/ {0 “5“” ,I’ to r/masr V'O/ 4/0 WWW 5 dy'vc WW7 uw : if (i) (10) 2. In California in 2004, there were about 75,000 companies engaged in retail trade. About / 67,000 of these had fewer than twenty employees. The table below shows the distribution / of the size (as measured by number of employees) of such companies. Number of employees Percent Firms with no employees 14 Firms with 1 to 4 employees 51 Firms with 5 to 9 employees 22 Firms with 10 to 19 employees 13 (a) Use the information in the table to draw a histogram for the distribution of the size of the companies. Please mark the horizontal and vertical axes carefully. Label the axes. (Remember to show your calculations.) Note: Crew)in ‘l/‘(IMJ‘J/ r19 hf “El-KC/“J‘gd // i \1 130 ? °/~ r” 3"" g 2“ W é K lg My ,9” . l k 0\ ' s’ m J - 1;! . . 7“ mum/dam 0:? M» Plot/{ii C. «h l'W'VW (b) In 2004,;1w companies (in retail trade in California) had either 9 or 10 employees? a o r .p F. ' (a W i W “ 5'77 /o °“ “0”” (c) What assumption did you make in arriving at your answer in part (b)? r . 2-” ~ .. 13cm W. "' - r or" am Tye}, rfiianr-f’ d LAM?” W" " H; ' b H 'W 5‘: ‘c a grout? f (Note: The information in the table is based on data available at: http://www.census.gov/epcd/susb/2004/ca/CA44.HTM ) For the men and women age 18 to 24 in the HANESZ study: men: average height = 69.6 inches, women: average height = 64.3 inches, Both histograms followed the normal curve. Fill in the blank below: The 15th percentile of height for the men is the women. Q2 SD = 2.8 inches SD = 2.6 inches / th percentile of height for the /,/l10) 4. (a) Find the correlation coefficient between X and y for the data set below. Show your / calculations. ’ W W W ,3!” )7 v 1'? AV \/ — r m wva .. _ aV \l ' ' ’ A. . > r\ v H [kl—Eif’b‘rl’filvfi, S“) y __ 2 §)/ ’77» l a a , \ 7 {lrnflat {mnf/N’ W” 74 7" 7) J H §pv :: / WWW _ a '3 3 l a '”- ru~ 31 “I ‘L ‘r n 1“ ’6 ’) l l ‘1 s 7(7) "' /0 r \ 2 W»\. \70. ' l"+ '2-2’ 9» (f Z‘\\+.)§+Ui..k \ ‘1 U 53“ 1 ‘ “l 1;: ( av 0 r a...” «v 3' "‘5 my " ’ f A, s k} yUC.‘-A.( A v H mm“ z;Alex;game,» Va 7 We“; w”, 4”"). ,/ 3 4'5 Z L' L033 7 .1: IS 7 _ 5 e . 3 ' fl 0 . / 0 7 -5 . 3 , l5 'L’ - ° / r» ‘2‘? 'L f ( ’ g; I I 3' ? 2 , .- M . ‘. IV ' K “"17 W‘ / " 3’. u l' ) ‘ ML” ' f l mam470::.&M«.»7W7 '3 J—U , "LG 23,1” 3 71 W -, a v r 5 (b) True or false, and explain: For the data above, the point (13, 18) will line on the regression line for predicting y from x. fl/M, Pail/Hi wt” Om iii/155"?” n f r a v’ / )y/A 47y fife/{24' fl Vv / (I; (5) 5. The scatter diagram below shows some hypothetical data. 15 XXXXXXXX XXXXXXXXX XXXXXXXXXX XXXXXXXXXXX XXXXXXX XXXXXXXX XXXXX 1xxmxxxxxxxx X XXXXXXX —XXXX)<XX XXXXXXXX ‘XXXXXXXX —-XXXX><XXXXXXXX><XX><X i TIIIr—Tllillr-T‘| 5 10 15 N O (a) For this data, what is the slope of the regression line for predicting y from x? Your answer can be an estimate, but give the reasoning you used to arrive at the estimate. ’ 3l‘~' V34 ‘9‘“ jag la a ’ \flm ac @ c x v’ C) D c » j/lu? {at 11/ g - ~ ,w wmmr‘mm’rkgkn, ax “Yuri _ v \r: ' a 9 . "‘47=~«-~-—1 “ v t, , a, r -0 (b) For the same data, fill in the blank below with a number: \ ‘1 G \ r.m.s. error of the regression methdlilx= (P 5}) g x r.1‘n.s. error of the baseline method (Both methods are being used to predict y from x.) Again, your answer can be an estimate, but give the reasoning. 1‘7 :0 \’ l A h" \ ’ “‘ 4~ / y 3 < 5 6 i l 1/ ’ I, I O a l a g / (10) 6. A study involves 2500 men age 18 to 24 enrolled in a fitness program. Some descriptive statistics from the study are shown below: height: average = 70.5 inches, SD = 3.0 inches weight: average = 165 pounds, SD = 30 pounds Correlation = 0.55 The scatter diagram is football shaped. The investigators used the regression method to estimate weight from height for each of these men, and then divided the men into two groups according to how well the regression method estimated their weight: (i) those for whom the regression method was off by 10 pounds or less. (ii) those for whom the regression method was off by more than 10 pounds. (a) One man in the study was 6 feet tall and weighed 180 pounds. Which group does he belong to: (i) or (ii)? / » figfi 55'} r .275 , W ‘r‘mcl’wi 2 '7 : . S— .._3 O 6'7<é/O 1 30 L ’ 27g : fijbg 2+2 Bah)ny w (b) About What percent of the 6 foot men in the study belong to_ group (1)? ~ / :7 — .4 [ ‘hg‘: Exfyv‘ ‘ l V {ffigg‘y}? v X fl. ...
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This note was uploaded on 10/12/2008 for the course STAT 21 taught by Professor Anderes during the Fall '08 term at University of California, Berkeley.

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Stats21_Purves_07F_Midterm1 - , (5) 1. The quotation below...

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