Answer Key Essay Example

Answer Key Essay Example Answer Key Essay Answer Key Essay Professor Mumford [emailprotected] edu Econ 360 Fall 2012 Problem Set 1 Answers True/False (30 points) 1. FALSE If (ai , bi ) : i = 1, 2, . . . , n and (xi , yi ) : i = 1, 2,  ·  ·  · , n are sets of n pairs of numbers, then: n n n (ai xi + bi yi ) = i=1 i=1 ai x i + i=1 bi yi 2. FALSE If xi : i = 1, 2, . . . , n is a set of n numbers, then: n n n n n (xi ? x) = ? i=1 n i=1 2 x2 i ? 2? x i=1 xi + i=1 x = ? i=1 2 x2 ? n? 2 x i where x = ? 1 n i=1 xi 3. TRUE If xi : i = 1, 2, . . . , n is a set of n numbers and a is a constant, then: n n a xi = a i=1 n i=1 xi = a n x ? here x = ? 1 n i=1 xi 4. FALSE If X and Y are independent random variables then: E (Y |X) = E (Y ) 1 5. TRUE If {a1 , a2 , . . . , an } are constants and {X1 , X2 , . . . , Xn } are random variables then: n n E i=1 ai X i = i=1 ai E (Xi ) 6. FALSE For a random variable X, let  µ = E (X). The variance of X can be expressed as: V ar(X) = E X 2 ?  µ2 7. TRUE For random variables Y and X, the variance of Y conditi onal on X = x is given by: V ar(Y |X = x) = E Y 2 |x ? [E (Y |x)]2 8. TRUE An estimator, W , of ? is an unbiased estimator if E (W ) = ? for all possible values of ?. 9. FALSE The central limit theorem states that the average from a random sample for any population (with ? nite variance) when it is standardized, by subtracting the mean and then dividing by the standard deviation, has an asymptotic standard normal distribution. 10. TRUE The law of large numbers states that if X1 , X2 , . . . , Xn are independent, identically distributed random variables with mean  µ, then ? plim Xn =  µ 2 Multiple Choice Questions (a) ceteris paribus (b) correlation (c) causal e? ect (d) independence (20 points) 11. The idea of holding â€Å"all else equal† is known as 12. If our dataset has one observation for every state for the year 2000, then our dataset is (a) cross-sectional data (b) pooled cross-sectional data (c) time series data (d) panel data 13. If our dataset has one observation for every state for the year 2000 and another observation for each state in 2005, then our dataset is (a) cross-sectional data (b) pooled cross-sectional data (c) time series data (d) panel data 14. If our dataset has one observation for the state of Indiana each year from 1950-2005 then our dataset is (a) cross-sectional data (b) pooled cross-sectional data (c) time series data (d) panel data 15. Consider the function f (X, Y ) = (aX + bY )2 . What is (a) 2aX (b) a(aX + bY ) (c) 2a(aX + bY ) (d) a2 X ? f (X,Y ) ? X 3 Long Answer Questions (50 points) 16. The sum of squared deviations (subtracting the average value of x from each observation on x) is the sum of the squared xi minus n times the square of x. There are ? several ways to show this, here is one: n n xi (xi ? x) ? i=1 = i=1 n (xi ? x + x) (xi ? x) ? ? ? n = i=1 n (xi ? x) (xi ? x) + ? ? i=1 n x (xi ? x) ? ? = i=1 (xi ? x)2 + x ? ? i=1 n (xi ? x) ? (xi ? x) = 0, so ? and we know that i=1 n i=1 (xi ? x)2 ? 17. There are several ways to show that this expression equals the sample covariance between x and y, here is one: n n xi (yi ? y ) ? i=1 = i=1 n (xi ? x + x) (yi ? y ) ? ? ? n = i=1 n (xi ? x) (yi ? y ) + x ? ? ? i=1 (yi ? y ) ? = i=1 (xi ? x) (yi ? y ) ? ? 18. Correlation and causation are not always the same thing. (a) A negative correlation means that larger class size is associated with lower test performance. This could be because the relationship is causal meaning that having a larger class size actually hurts student performance. However, there are other reasons we might ? nd a negative relationship. For example, children from more a? uent families might be more likely to attend schools with smaller class sizes, and a? uent children generally score better on standardized tests. Another possibility is that within a school, a principal might assign the better students to smaller classes. Or, some parents might insist that their children are in the smaller classes, and these same parents tend to be more involved in their children’s education. Given the potential for confounding factors such as these, ? ding a negative correlation between class size and test scores is not strong evidence that smaller 4 class sizes actually lead to better performance. Thus, without other information, we cannot draw a meaningful economic conclusions. A correct answer should explain that we should be careful about drawing economic conclusions from simple correlations. (b) The sample correlation between N and T is de? ned as: s rN T = N T sN sT where the sample covariance, sN T , is given by: sN T = 1 999 1000 ? Ni ? N i=1 ? Ti ? T and the sample standard deviations are given by: sN = 1 999 1000 Ni ? N i=1 2 sT = 1 999 1000 ? Ti ? T i=1 2 Note that there are several alternative ways to write this and statistical programs generally use other algorithms to calculate the correlation that are less prone to loss of precision due to roundo? error or storage over? ow. 19. Wage data (a) There are 526 observations. (b) There are 274 men in the sample. This means that the sample is 52. 09 percent male. (c) The average level of education in the sample is 12. 6 years. The median level of education is 12 years. (d) The highest education level in the sample is 18 years of school. 9 people in the sample report having 18 years of education. (e) The average hourly wage in the sample is $5. 90. The median hourly wage in the sample is $4. 65. 20. Fertility data (a) There are 363 women in the sample. (b) The average number of children ever born to a woman in the sample is 2. 3. The median number is 2. (c) The largest number of children ever born to a woman in the sample 7. Six women report having seven children. (d) 25 percent of the sample lived in the eastern United States at age 16. (e) The average level of eduction in the sample is 13. 2 years. 5

Distributed Databases Research Paper Example | Topics and Well Written Essays - 1000 words

Distributed Databases - Research Paper Example 1). It is important to acknowledge that this article has outlined a significant set of valuable information about distributed systems. This is specifically on issues based on controlling concurrency of organization data and most importantly, the security of data and transactions handles by distributed database systems. The authors of the article address indicate that concurrency control and security threat is a very crucial subject of concern in distributed database networks. The article goes further to clarify that there has been no guarantee of execution of secure database transactions in most distributed databases. Specifically, the author outlines that, there is no clear platform for ascertaining that database transactions are always maintaining the ACID properties, which are atomicity, Consistency, Isolation and Durability (Vinod et al. 3). This paper describes that there are a number of concerns in the design of most distributed databases, which have negatively affected the performance of their respective distributed networks. Specifically, concurrency issues in the transfer of data along with security of the transactions handled by these systems have been indicated as significant subjects of concern. In a distributed database, the database spread over a wide number of computers, which communicate and share data via a well designed of computer data network. The database applications connected to the distributed database system have to work transparently on the database fragments (Vinod et al. 2). The paper outlines that concurrency control is a database management activity that focuses on coordinating database manipulation processes by a concurrent access to data while potentially interfering with one another. The main subject of concern in concurrency control is to ascertain serialisability of transactions

The Way People Treat Animals Essay Example | Topics and Well Written Essays - 1000 words

The Way People Treat Animals - Essay Example Catharine A. Mackinnon has a very feminist view on the exploitation of animals, she compares the state of animals to the state of women, she thinks that women and animals are both exploited and have more similarities than one. She claims that animals are treated like women and women like animals, this again goes to show the sheer exploitation of both women and animals. She goes on to say that women are as badly treated as animals, she is aghast when she makes this comparison and she is right in many ways, women are still being exploited in some areas of the world and so are animals. â€Å"People dominate animals, men dominate women.† (Animal Rights, P277) The author sheds light upon how women and animals are being dominated in our society. She throws light upon the inequality that prevails in our society. The author brings out an excellent ideology; the suppression of both women and animals is because they are considered inferior, women are exploited because they are considere d biologically weaker, animals are exploited because they are considered much inferior to the human race, the exploitation is purely based on the ideology of inferior and superior, a superior being starts believing that it is his right to suppress the inferior, the same has been highlighted by the author. The author is labeled to be a feminist because she talks about the male ideology and brings out the similarities in animals and women. â€Å"Qualities considered human and higher are denied to animals as qualities considered masculine and higher are denied to women.† (Animal Rights, P278) The lesser humanity of women is conceded by men and they call women animal names like chick, bunny, bitch and so on, this again points to the inferior nature of women in the society, animals are lower than humans is also a presumption which with several human beings live with. The author also talks about the ridiculous ways in which both women and animals are exploited, rats are put in the vagina of women and it is thought that the rat would suffer much more than the women, the author tries to say that the status of women is lower than the status of animals. Misery and exploitation are common amongst women and animals, men find new ways to exploit and dominate both. The author talks about the laws that have been made to protect animals, films showing the crushing of animals have been banned by the government of the US but she says that there are no such laws in place to protect women who are also being exploited sexually by men. She concludes her argument by saying that women are better off without laws. Elizabeth Anderson has a different take on the same matter, her analysis cannot be called a feminist view, and she does not juxtapose animals with women, the author bases her argument on intrinsic value of animals. The author talks about the animal rights, she says that chimpanzees are believed to have the mental ability of a mentally retarded child, chimpanzees are b eing used for several experiments, and can mentally retarded children be used for the same experiments? The author is directly comparing animals with human beings; the point is why we are not using mentally retarded children for experiments who have the same mental makeup as a chimpanzee has? This goes to show double standards in the society, a

Project Mercury and Its Legacy Essay Example for Free

Project Mercury and Its Legacy Essay In the twentieth century, the United States and the Soviet Union engaged in a competition called the Space Race. This was a race to who would be the first country to send a rocket and a human being up into space. Although the Soviet Union was the first to send both a rocket and a human up into space, the United States successfully carried out a space mission called Project Mercury. Project Mercury was carried out in 1959 and came to a conclusion in 1963. It was the first human spaceflight program that was undertaken by the United States National Aeronautics and Space Administration (NASA). From when it was first introduced, to when the space mission was carried out, and when it had succumbed to its end, Project Mercury became an important mission which left one of the greatest legacies in United States history. In the initiation of Project Mercury, the government began a search for seven great Americans who would become United Statess first astronauts. To be considered for the position, the Americans had to meet some requirements, which were as follows: needed to be test pilots, needed to be no taller than 511, needed to weigh no more than 180 pounds, needed to be under the age of forty, needed to have a Bachelors degree or equivalent, have 1,500 hours of flying time, and have qualifications for flying jets. In addition to the requirements, the pilots had to go through rigorous testing and training that would assure that they were capable handling problems the spacecraft and the flight may pose on them. Out of the handful of pilots who met these requirements, only seven were chosen to become Americas first astronauts who were Alan Shepard, Gus Grissom, John Glenn, Scott Carpenter, Wally Schirra, Gordon Cooper, and Deke Slayton. Since these flights were going to be manned, NASA contracted Max Faget as the primary designer, along with a team of engineers to build the Mercury Spacecraft. Its design was a cone-shaped one-man capsule with a cylinder mounted on top. Two meters (6 ft, 10 in) long, 1.9 meters (6 ft, 2 1/2 in) in diameter, a 5.8 meter (19 ft, 2 in) escape tower was fastened to the cylinder of the capsule. The blunt end was covered with an ablative heat shield to protect it against the 3000 degree heat of entry into the atmosphere (Mercury Spacecraft). This design would be the first capsule that would go up into space. Project Mercury was finally undertaken after all of the seven American Astronauts were physically and mentally prepared, the spacecraft was built, and the rockets were safe to launch. Before America could send the first human up into space, they needed to make sure that the rocket was not going to blow up as it had done in launch tests. Engineers and scientists were working hard to accomplish this, but trial after trial, the rockets were always blowing up. Finally, NASA was able to perfect the rocket, and on May 5, 1961, Alan Shepard was the first American to be launched into space on the spacecraft called Freedom 7. This event was one of the greatest moments for America which anticipated further launches into space to explore what is beyond Earths atmosphere. The second flight was manned by Gus Grissom who was launched into space on the spacecraft called Liberty Bell on July 21, 1961. He successfully was able to complete a suborbital flight, but as he landed, his spacecraft hatch blew open and NASA was not able to recover the spacecraft. The first American to orbit the Earth was the third flight using the Friendship 7 spacecraft that was manned by John Glenn on February 20, 1962. He was only able to orbit the Earth three times due to concerns about the spacecrafts heat shield. Then, on May 15, 1963, Gordon Cooper became the first American to be in space for over a day and successfully orbited the Earth twenty-two times using the Faith 7 spacecraft. He was also the last American astronaut to be launched into space alone. Ultimately, Project Mercury came to its end creating one of the greatest legacies of United States history. The overall cost for Project Mercury added up to $1.6 billion in inflation-adjusted dollars (Program Cost). There are numerous legacies that Project Mercury left to Americans. One of those legacies is the will of America to continue the space programs after President John F. Kennedy said that this nation should commit itself to achieving the goal, before the decade is out, of landing a man on the moon and returning him safely to the earth (President Kennedys Challenge). Also, Project Mercurys greatest legacy is that it was United States first successful human spaceflight program. Project Mercury also influenced author Tom Wolfe who wrote the book The Right Stuff, which was later developed into a movie directed by Philip Kaufman. In conclusion, from the inception and up to the end of the space program, Project Mercury was a prominent accomplishment for the United States, leaving one of the greatest legacies for America. It changed the game of how America would accomplish its goals of becoming the first country to send an astronaut to the moon. At the end, the seven American astronauts who were chosen to be part of the space program will always be part of United States history and Project Mercury will continue to be the reason for where we are today pertaining to Americas advanced space program.

Sports Agents Essay -- History Athletics Sport Agent Essays

Sports Agents People have been entertained by sport since before the gladiators in the Roman Coliseum. In the 20th century, the publics’ passion for sport consumes more and more of their free time. As sports figures became internationally recognized, athletes began to realize their need for professional representation. Thus, sports agents were born. The field of sports agents has grown since then into an enormous field. Agents now deal with every aspect of an athlete’s life. Agents can be considered professional mangers who find the best place for their client’s talent. Sports Agents have not been around for a long time. â€Å"Until the 1970’s, very few players had agents because teams would not deal with agents (Masteralexis, 244).† Many times players found that having an agent was a disadvantage to them. For example, â€Å"In 1964 Jim Ringo brought his financial advisor (agent) to help negotiate a contract with Vince Lombardi of the Green Bay Packers. Lombardi excused himself for a minute, when he returned he told the agent that he was negotiating with the wrong team (Masteralexis, 244).† Agents had been around since prior to the 70’s, but were few and far between. C. C. â€Å"cash $ carry† Pyle is though to be the first Sports Agent. The first account of negotiations came when Pyle â€Å"Negotiated a deal with the Chicago Bears for Red Grange to earn $3,000 per game and $300,000 in endorsement and movie rights (Masteralexis, 244).† A few years later Babe Ruth allegedly consulted sports cartoonist Christy Walsh to serve as his financial consultant through the depression. These early accounts are the beginning of the Sports Agent. It took years for the agent to develop however.   Ã‚  Ã‚  Ã‚  Ã‚  Since the 1970’s the Sports Agency business has sky rocketed. There are five main factors that account for this. The reserve system is the first factor that lead to the growth of the Sports Agent. The reserve system was a restrictive system that limited the free, or open market. This enabled owners to retain rights to players and depress their salaries. Major League Baseball had the first system, which consisted of two parts, the reserve clause and the reserve list. The reserve clause stated that each player’s contract could be renewed by the team season after season, for as long as the club wished. The reserve list was sent to each team by the league. Teams had to place the names of r... ... sport, but is generally under five years. Therefore, it is the agent’s job to maximize earning potential during and after the athlete’s playing career. At the same time it is the agents job to protect the athlete from overexposure. â€Å"The agent must balance the need to maximize exposure with doing what is best personally and professionally for the athlete† (Masteralexis, 1998). This function also includes the agent investing time, energy, and money into the athlete’s career before the player has made it big. If the athlete’s career doesn’t take off, this results in the agent losing money. Dispute resolution follows career and post career planning on the list of functions. Dispute resolution is somewhat self-explanatory. It includes the agent resolving disputes with the league, team, teammates, fans, referees or umpires, the media, and endorsement companies. â€Å"Renowned baseball agent Dennis Gilbert likens the role of the agent to a shield, stating that it is the agent’s task to shield the athlete from the headaches that go along with resolving disputes† (Schwarz, 1996). This so called â€Å"shield† allows players to concentrate completely on their sport, without outside distractions.

Child Beauty Pageants Should Be Banned

Child beauty pageants should be banned Child beauty pageants should be banned because they cause children, especially little girls, to use artificial means to boost their self esteem. People were not born with makeup, spray tans, big hair, and false teeth. Beauty pageants set false rules on beauty. They make children believe they have to wear make-up, jewelry, wigs, fake nails, and other acessories to be beautiful. Every child is beautiful in their own way. Their beauty is natural and they shouldn't have to have anyone's opinion on the way they look.Beauty pageants can also cause serious mental and health issues. They can lead to depression, anorexia, suicide, and many other serious issues. Children might starve themselves to lose which could lead to eating disorders. Beauty pageants can cause depression, and depression may later lead to a suicide Children shouldn't be forced to be in pageants. Mothers try to live their dream through their children. Children shouldn't get their lives taken away from them.They only get one childhood, they don't get it back after it's over. Any parent placing their child in these types of pageants, based solely on looks, is giving their child the attitude that appearance can get you anywhere in life. It is wrong to teach children that looks are the most important asset to possess. I am not stating that children shouldn't be encouraged to develop a talent or skill, and compete with that talent or skill, I am stating that competing over looks is sending the wrong message to children.

Outline of Ancient Greece Society and Culture - 1833 Words

Classes of citizens Aristoi (Upper Class) †¢ Citizens without jobs †¢ Had slaves attend to their material needs †¢ They lived in leisure Metics (Middle Class) †¢ Largely non-citizen working class Periokoi (Lower Class) †¢ Mostly freedmen who at one point had been slaves †¢ Usually not citizens †¢ Ceramic Industry owned by the middle class †¢ Made sure the navy fleet was maintained Slaves †¢ Rescued infants †¢ prisoners of war †¢ criminals †¢ victims of slave raids †¢ Very few Greek slaves †¢ Slaves were whipped when they misbehaved †¢ Most people were kind to their slaves Roles of men †¢ Men were in charge of the family or household. †¢ Treated with great respect †¢ Men laid on couches and had slaves attend to them while eating dinner †¢ Women and children ate in separate room. †¢ Considered the most important people in ancient Greece. Roles of women †¢ Not allowed to eat or sleep in the same room as men. †¢ Not allowed to go to the Olympics or marketplace of a city. †¢ Ran the household and managed the slaves. Roles of children †¢ All girls were taught how to cook, weave, and clean †¢ Girls of wealthy families were expected to marry the man their father chose for them at age 15 †¢ Boys were considered more important than girls †¢ Went to school at age 6 †¢ Learned to read, write, and add †¢ Expected to have a healthy mind and body †¢ Began to train for the their future jobs at age 16 Events 1. The Battle of Thermopylae †¢ Took place in 480 BCE †¢ Between the Greeks and the Persians †¢ First battle inShow MoreRelatedThe French Revolution Essay examples1018 Words   |  5 Pagesbetween the French Revolution and the age of antiquity, more specific Ancient Greece. 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