F08_Mid1_keyA

F08_Mid1_keyA - Economics 41 UCLA Fall 2008 NAME (Print)...

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Unformatted text preview: Economics 41 UCLA Fall 2008 NAME (Print) October 20, 2008 Midterm Exam I. TA Name & section time: - The normal table and some formulas are on the last page ofthis exam - Only pens, pencils, and erasers may be used — this is a closed book, closed note, exam. — Students may use an ordinary calculator, but nothing that can access the internet. - This exam consists of 15 'l'rue/False ? (30 points) and 10 short answer ? (30 points) and 4 problems (40 points). - Clearly write answers on this exam. No points are awarded for illegible answers. - Be prepared to show a photo ID during the exam (cg, UCLA 1D, driver’s license, or son'iething similar). - You may leave when finished. Turn in both the exam and your seantron. Do not disrupt those still taking the exam. I. Circle either T for True or F for False (2 points each, 30 total). 1f F A sample correlation coefficient may be calculated between two quantitative variables, but NOT two qualitative (-— eategorieal) variables. a. 2) T eifF‘ :gTime series data on one variable can NOT be represented in a histogram. 3) '1‘ or' F ' If the sample correlation coefficient between X and Y = 1, then the slope of an estimated regression line of Y on 'X for the same data sets must also = 1. CULT/hr F The US. national “federal government budget deficit is a flow variable. . Cm d S) T orf'li‘,:’For all boxplots, the “whiskers” extend to the furtheSt observations which are less than 1.5 quafliles below the firstl'quartile, or 1.5 tiles above the third quartile. (9 :2) 6(Tpr F For a histogram with relative frequency on vertical axis, one can not determine the number of observations 2’“ . . . . . . t. - 7) 'l‘ orLE/l'l'he slope estimate for an ordinary least squares regression is “rcsxstant to outliers, but not the sample correlation coefficient 8) '1‘ or‘ li‘fi'only data from a population that is normally distributed can be “standardized.” 9) T or-{F ,iFor any “reverse regression” the estimated sIOpe: b‘, is the reciprocal of the estimated 510pe of the forward regressioii: bl ) z—y . . . . . l ‘1 . . 10) T or® Since the formula for the probability of a normal distribution = e a the normal probabtltty O'x/E density curve is highest when (x—ti) is largest. 11) T or® For three observations: 3, 4, and 5, the sample standard deviation 2 .8165 "t 0" - 12) (Elor F s! is a statistic, while Ox is a parameter. EXT/or F An observation may he an outlier in umvarate analySIs, but not bivariate. 14) '1‘ or®An outlier must be an influential observation. 15) T oré) If the sample correlation coefficient : 1, then we can be Confident that changes in X cause changes in Y. 5 L51; . ' Ct tr {aw-fl [Butt ; a .: ..- 1.2. - it? It" 1 I I. ,I ._ ll. BRIEFLY, clearly and correctly answer the following ten questions (3 points each, 30 total). 1) The time required for individuals to complete an exam is normally distributed with mean = 56 minutes and a standard deviation 01'4 minutes. If students are given @116 hour to finish, find the proportion who will eornplete the exam. .. . ,_ __ Jo. .. r r'n ‘ fl m... w _ . “I, i ‘ x ‘ -" ‘ II If; ,2 L l 3'; 1" if It . . I Z_ 2) The scores on a university examination are normally distributed with a mean of 50 and a standard deviation of IO. If the top 16 % of students earn A‘s, what is the lowest mark that a student can have and still earn an A? " Z s t >< —- w -= f ‘ HZ 4- '-\ '- .94/3 .. .. m ‘A' ' p m riot} 2;. 5t: Bette: g, (1: 3) An economies department with 40 all—male faculty which hires two per year, has two retirements per year (each after a 20-year career) wants to have 25% female faculty. What willbe the gender ofthe flow of new hires it'this goal is to be met in 10 years? 1 all“, .. . I ' .a.. I. r . t . , _ __ Fm l ‘ o' k ._ . I" I , n r ir'ir ’.\ '_: .5." f " I3!" {H K' \ Lr \ f ' ': '- 1 - '_.‘- 1/ .2 4) For an ordinary least-squares regressienline, if x = f , what is the predicted height of the regression line for this I \. x? '. i f 5) The average earnings of individuals with an undergraduate degree in economics is higher than for individuals with an undergraduate degree in business adnu'nistration. Briefly give three reasons provided in class. -_— . K ;' my : . . r. -% 6) Use the regression output below. The dependent variable, W = hourly wage. The independent variable. LOS = length of service (in months). What is the predicted wage of a worker with 10 months of “service” (experience)? Regression Statistics ’ Coef. I I . .._ , Intercept 8.0 . r ' ’ ' LOS 0.40 I .' l4») I 5 T \',‘ fl 7) The diagram below show the number ofjumps for each of 24 student. The variable we consider is number of jumps. ’ _._ "_ ‘ x 'J/ - . i , x x twfllui'” ‘2 x x u' x x x \ x x x )r x x x I x x x x x, X x x x/ ” . . i 1‘ _ e I H.....Lt. I I‘: '( . ...! ‘ Jus‘tp's ( ]'--.\ / \, F I a. I . ’ \ i What is the median . é ,3 ;and the mode: -' ‘2' ? 1 -' B) In the formula from the text and class: e 2‘ " , what is the numerical value, - (three significant digits)? " ' - 0' 27? 1‘ 1, ,, ... 3“ t‘.‘ . . . r , -. 2. ' 3 9) What is minimized in fitting an ordinary least squares regression line? Use summation notation. not words. 7 "’ i “A I. . t ‘ d to; 3;:- ~11 2 -' 10) A sample othO'ih/orkers are Classified race. A bar graph of the results is given below, but the bar for blacks in the graph below has been omitted. What is the pmportigy ofblaek workers in the sample? a) _' _, H ’ . . a. I _. < - E- .. I . . " / r 2 IN)“ 'L' e-J D A o m ‘ O . 2) I I ' l n l l 1 ' | 1 white black astan other III. Clearly, concisely, and completer answer the following problems. Show your work. (10 points each, 40 total). 1) Let X hourly wage for a sample of9 workers. The values ofX are: 30, 34, 5.5, 15, 20, 18, 25. 18, 28 a) Make a sternplot to the far right (do not “split stems”) and a histogram with classes: 10-20,, _20—3Q,-ete. below. as-done in the text (with lower but not upper values included). {'1 “*1 J I; _. _ “ II What is the Median? J I _a. ‘-I hh— - - . . . , If I . . l r?) r.) I ' c) What IS the First Quartile, Qt? it is} ; Third Quartile, Q3? t -' "W F: - —~_~, (use text’s method to find Q. and Q;.-hin"t: :-) L” l ' i '. d) What is the Interquartile Range (IQR)? _ .; \. . r,“ 5" '3 1.‘ 5'" 2) Consider the following data on X and Y: 3) Find value 'forf‘m. 0;)»,4 |l_ ii) 20%;);1 7.» 7 _ Sump 4 .I_( t _ LID-!"; ._ . I 1 . \~. I~..H --- . > J? .. 111) (2%) = [2. l "1.60 ‘ l“*‘j.;::..'.;,';i'._,,.,.....--;-_-r' ’ 3 7—2,, ~ .. gr I- t x 1 ' ‘ _ ‘ t m .a g ' - '- ' xx“ if» F (if)... 24‘ (g r) __ 12L} \(Il )1.” I] b) Use either your calculator or the formulas on the last page to find: _ t. l/E — l S ""' f :3 Q t i) sample correlation eoeffieient’.’ ,n-‘s bl ”‘ H ' ‘3 -l ‘93 £3 ' —-— it --’ (I) ' ii) slope of the estimated 0L5 regression lin , with x the independent variable iii) intercept of the estimated OLS regression line, with x the independent variabli .— D I I _ 4' a " A; ho : x; » lax: e— - {fig ~. ?./5 + Halls: true {this .. 3i ConteTa'e'r‘Eicél'6625:1135Elie right.- ' I I h ' m' ' " ‘I M Y = overseas returns (in %) and X = U.S. returns (in %). Mun'p'e R 06000 )7 _ 3 d )7_ _ 4 d _ 6 R Sguare 0.3600 _ an ? — 5 SK _ an S" '— Coefficients \)=-- Z 2 i H x H Intercept 2.30 a) For the forward regression Y = hL+bIX what is the predicted US 0.90 I x - -’" "x -_ '4' — —%——-——H mine for overseas returns if é. __ 25 hi ..'6 {3: I if US. returns are: -5 percent? __ I U.S. returns are 11 pereentg r2! 2 :. '3 w - b)AF0r the “a “P- regression X f b’hil-b’lYu___\vltat is the predicted value for U.S. returns-if f" I fl I+ ' t! g! j I. l 3‘ .. .- L Overseas returns..,are: —5 pereent’fi ‘— 1 Overseas returns are ll pereentfi s l i H 'qu 31")“ K... _ - '1' [£4541] - .. "it. Wj'r'mgaare‘n‘t; p'Sfiutatiahfassmne test "scoics follow"a'n'ormrtristribntibrr'wini'populates mean? 600‘ and ‘ ' ' "‘— population standard deviation 2 80 J _, .3\ 2.9—0 <2" '1 a) The standardized z-score corresponding to a raw score X = 800 = '3 xii; ‘_’ b) What proportion ofthis population scored below 800?@r5 % )1 I t. ‘ 1‘ 1 _ ' C? 39 L .1; P I E a . . . -2St‘-’fl " ‘” c) What prOportlon ofthts population scored between 650 and 800?\<n__ ~E~ 9;) ‘ I P [:3 y "- r" - "" r- I! :5": ‘“'-..._ ' I ‘2 quf‘)““ 5,335} * '3‘='“f=‘i d) What test score would a student need to have a higher score than 90% offlthcpopulation? “‘x a I wit—(gnu —, Hg x“ GOD-L132}: .KW/ag'gf >1 .dri" e) What test score would a student need to have a higher score than 80%"6ftfie'p0pulation? fix 3t} . X“._.._b_” \(3 6004 67.2 -‘ (>6 423 t“ \ ...
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This note was uploaded on 12/06/2009 for the course ECON 41 taught by Professor Guggenberger during the Spring '07 term at UCLA.

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F08_Mid1_keyA - Economics 41 UCLA Fall 2008 NAME (Print)...

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