Inferential Statistics Essay Example for Free

Inferential Statistics Essay With inferential statistics, you are trying to reach conclusions that extend beyond the immediate data alone. For instance, we use inferential statistics to try to infer from the sample data what the population might think. Or, we use inferential statistics to make judgments of the probability that an observed difference between groups is a dependable one or one that might have happened by chance in this study. Thus, we use inferential statistics to make inferences from our data to more general conditions; we use descriptive statistics simply to describe whats going on in our data. Here, I concentrate on inferential statistics that are useful in experimental and quasi-experimental research design or in program outcome evaluation. Perhaps one of the simplest inferential test is used when you want to compare the average performance of two groups on a single measure to see if there is a difference. You might want to know whether eighth-grade boys and girls differ in math test scores or whether a program group differs on the outcome measure from a control group. Whenever you wish to compare the average performance between two groups you should consider the t-test for differences between groups. Most of the major inferential statistics come from a general family of statistical models known as the General Linear Model. This includes the t-test, Analysis of Variance (ANOVA), Analysis of Covariance (ANCOVA), regression analysis, and many of the multivariate methods like factor analysis, multidimensional scaling, cluster analysis, discriminant function analysis, and so on. Given the importance of the General Linear Model, its a good idea for any serious social researcher to become familiar with its workings. The discussion of the General Linear Model here is very elementary and only considers the simplest straight-line model. However, it will get you familiar with the idea of the linear model and help prepare you for the more complex analyses described below. One of the keys to understanding how groups are compared is embodied in the notion of the dummy variable. The name doesnt suggest that we are using variables that arent very smart or, even worse, that the analyst who uses t hem is a dummy! Perhaps these variables would be better described as proxy variables. Essentially a dummy variable is one that uses discrete numbers, usually 0 and 1, to represent different groups in your study. Dummy variables are a simple idea that enable some pretty complicated things to  happen. For instance, by including a simple dummy variable in an model, I can model two separate lines (one for each treatment group) with a single equation. To see how this works, check out the discussion on dummy variables. One of the most important analyses in program outcome evaluations involves comparing the program and non-program group on the outcome variable or variables. How we do this depends on the research design we use. research designs are divided into two major types of designs: experimental and quasi-experimental. Because the analyses differ for each, they are presented separately. Experimental Analysis. The simple two-group posttest-only randomized experiment is usually analyzed with the simple t-test or one-way ANOVA. The factorial experimental designs are usually analyzed with the Analysis of Variance (ANOVA) Model. Randomized Block Designs use a special form of ANOVA blocking model that uses dummy-coded variables to represent the blocks. The Analysis of Covariance Experimental Design uses, not surprisingly, the Analysis of Covariance statistical model. Quasi-Experimental Analysis. The quasi-experimental designs differ from the experimental ones in that they dont use random assignment to assign units (e.g., people) to program groups. The lack of random assignment in these designs tends to complicate their analysis considerably. For example, to analyze the Nonequivalent Groups Design (NEGD) we have to adjust the pretest scores for measurement error in what is often called a Reliability-Corrected Analysis of Covariance model. In the Regression-Discontinuity Design, we need to be especially concerned about curvilinearity and model misspecification. Consequently, we tend to use a conservative analysis approach that is based on polynomial regression that starts by overfitting the likely true function and then reducing the model based on the results. The Regression Point Displacement Design has only a single treated unit. Nevertheless, the analysis of the RPD design is based directly on the traditional ANCOVA model. When youve investigated these various analytic models, youll see that they all come from the same family the General Linear Model. An understanding of that model will go a long way to introducing you to the intricacies of data analysis in applied and social research contexts. The T-Test The t-test assesses whether the means of two groups are statistically  different from each other. This analysis is appropriate whenever you want to compare the means of two groups, and especially appropriate as the analysis for the posttest-only two-group randomized experimental design. Figure 1. Idealized distributions for treated and comparison group posttest values. | Figure 1 shows the distributions for the treated (blue) and control (green) groups in a study. Actually, the figure shows the idealized distribution the actual distribution would usually be depicted with a histogram or bar graph. The figure indicates where the control and treatment group means are located. The question the t-test addresses is whether the means are statistically different. What does it mean to say that the averages for two groups are statistically different? Consider the three situations shown in Figure 2. The first thing to notice about the three situations is that the difference between the means is the same in all three. But, you should also notice that the three situations dont look the same they tell very different stories. The top example shows a case with moderate variability of scores within each group. The second situation shows the high variability case. the third shows the case with low variability. Clearly, we would conclude that the two groups appear most different or distinct in the bottom or low-variability case. Why? Because there is relatively little overlap between the two bell-shaped curves. In the high variability case, the group difference appears least striking because the two bell-shaped distributions overlap so much. Figure 2. Three scenarios for differences between means. | This leads us to a very important conclusion: when we are looking at the differences between scores for two groups, we have to judge the difference between their means relative to the spread or variability of their scores. The t-test does just this. Statistical Analysis of the t-test The formula for the t-test is a ratio. The top part of the ratio is just the difference between the two means or averages. The bottom part is a measure of the variability or dispersion of the scores. This formula is essentially another example of the signal-to-noise metaphor in research: the difference between the means is the signal that, in this case, we think our program or  treatment introduced into the data; the bottom part of the formula is a measure of variability that is essentially noise that may make it harder to see the group difference. Figure 3 shows the formula for the t-test and how the numerator and denominator are related to the distributions.

The Pros and Cons of Massive Open Online Courses (MOOCs), Essays

An increasing number of universities and private companies are now offering free online college classes, many of which focus on computer science education. Technological advancements have enabled millions of students worldwide to participate in these free classes. This research paper will briefly describe the history of the Massive Open Online Courses (MOOCs), investigate the pros and cons of MOOCs as they relate to computer education and examine the potential ethical issues surrounding MOOCs. Free technical training and coursework, specifically MOOCs, provides the opportunity to bridge the higher educational divide and increase the technology skilled labor force but raise serious ethical concerns regarding intellectual property ownership and the privacy of personal information. The cost of a college education in the United States has increased 538% since 1985 (Jamrisko & Kolet, 2013). In the wake of the most recent recession, universities have seen their endowments shrink, public funding for state universities has decreased, the job market has diminshed and consequently, graduates are having a difficult time repaying their student loans (Yardi, 2012). As a result, there is a demand for more affordable higher education pathways. The creation of free, online college courses has provided a possible solution in the quest for an alternative to the traditional, expensive higher education path. The goal of free higher education for all is a lofty but admirable one. As the number of MOOC providers and course options increase, it is important to examine and critique the methods used to achieve this goal. Review of the Literature History of MOOCs Massive Open Online Courses (MOOCs) are online, tuition free courses that ... ...s? Retrieved from http://www.bostonglobe.com/business/2013/10/05/will-mooc-help-you-open-career- doors/pmjHbLCghsH0lEbulWC9VL/story.html Number of Students. (2014, January 17). Retrieved from https://www.coursera.org/about/community Robbins, J. (2013, March 25). The ethics of MOOCs. Retrieved from http://www.insidehighered.com/blogs/sounding-board/ethics-moocs Schmidt, P. (2013, June 12). AAUP sees MOOCs as spawning new threats to professors’ intellectual property. Retrieved from http://chronicle.com/article/AAUP-Sees-MOOCs-as- Spawning/139743/ Weigel, M. (2014, January 2). MOOCs and online learning: Research roundup. Retrieved from http://journalistsresource.org/studies/society/education/moocs-online-learning-research- roundup Yardi, Moshe. (2012). Will MOOCs destroy academia? Communications of the ACM, 55(11), 5.

Sylvia Plath’s Poetry Is Dark and Disturbing

From studying the unique poetry of Plath, I found it intense, deeply personal and somewhat disturbing as she wrote about the horrors of depression with ruthless honesty. Her poetry is personal in that she talks about a taboo subject that wasn't acknowledged during her lifetime and in a way it made her poems brilliantly intense. This can be seen most clearly in ‘Child’, ‘Elm’, ‘Poppies in July’ and also ‘Mirror’. ‘Elm’s’ tone is insanely intense, dark and plain miserable and this makes the reader feel immensely disturbed.It is clear from reading Plath’s work that she was in a dark hole, willing to escape. ‘Elm’ finished with the disturbing line â€Å"That kill, that kill, that kill†. We can see through her callous honesty and the unsettling atmosphere that she is tormented when she says â€Å"Till your head is a stone, your pillow a little turf†. Here, she is using an image of a g rave and this sense of mortality is extremely personal, many poets wouldn't write about such agitated thoughts. Her startling honesty is seen when she says â€Å"I am terrified by this dark thing†.Plath is afraid, she is desperate and she is reaching out to her readers, begging for help. Her use of words in ‘Elm’ is also interesting. â€Å"Faults† could be emotional and/or physical and this shows the psychological states explored throughout Sylvia Plath’s work. â€Å"Malignity† symbolizes evil and the intensity of how disturbed her life was. Another poem that describes the intense and disturbing life of Plath in a deeply disturbing and personal way is ‘Poppies in July’.This poem was written just after the break-up of the marriage to the love of her life Ted Hughes. In the unsettled atmosphere, it is evident that Plath is permeated with heartbreak and depression. Her anger is displayed through the disturbing use of the colour red, also symbolising danger. Poppies are usually a magnificent image of happiness and nature, but in Plath’s poem we can see through her dubious and appalling honesty that even the nice things in life are making her angry and upset, she can get no happiness from anything anymore. Colourless†Ã¢â‚¬ ¦ I feel an intense sadness for Plath as I read this poem because what she is aching for is help a human hand. She is looking for escape, oblivion, relief or neutrality, she can see no life worth living anymore and this makes ‘Poppies in July’ even more disturbing. Plath’s eccentric, queer and haunting writing is also seen in ‘Child’. This poem is very personal and although it is primarily a happy poem about her child there is an intense underlying sadness and emptiness. This poem is not angry, just negative, heartbreaking and regretful. Should† (the full quote would be better here) implies she wishes she was able to give her children somethi ng better, she is disturbingly sorry for not being able to give them everything they want and need. In this personal poem it is evident she loves her child very much and this is what makes it even more haunting and disturbing because she is so unstable and in a state of self-destruction â€Å"Your eye is the one absolutely beautiful thing†. We saw such anguish and hopelessness at the end of ‘Child’ when she says â€Å"This dark ceiling without a star†.I personally found this heartbreaking as it is so obvious how much she loves her child, but she knows that she is nearing the end; she can’t see any light in her life even though as a reader it is obvious that the light could have been her children. Therefore, I found ‘Child’ a disturbing and intense poem to study. Another poem by Plath that I found to be personal on an intense and disturbing way was ‘Mirror’. It is clear as Plath looks into the mirror that she is unhappy, wat ching her age. A mirror never lies, but Plath cannot find solace in what she sees.She fears herself as she sees her past and youth before her. â€Å"In me she has drowned a young girl, and in me an old woman rises towards her day after day, like a terrible fish. † Plath also called candles and the moon, both symbols of love and light. â€Å"Liars†: they both cast a shadow. This disturbing, empty thought clearly shows her tormented mind and that love is futile. The final poem I am going to discuss that shows Plath’s emptiness is ‘Finisterre’. Again, it is unsettling, negative and quite violent and shows her tormented state.I found this poem quite haunting and it shows the disturbing and intense time Plath was going through. â€Å"Whitened by the faces of the drowned†. The sea is also associated with death by Plath. â€Å"Souls rolled in the doom-noise of the sea†. Here, she is disconnected from the world, she also shows her disgust to o rganised religion when she says the Holy statue is ignoring the prayers of the people at her feet. With her callous honesty we can see that Plath can’t even find hope or rest in a God, she is well and truly alone. In conclusion, I found the poetry of Sylvia Plath to be intense, disturbing and personal.I enjoyed her poetry as everybody has off days so her poems are easy to relate to in the sense that everyone feels empty and unknown sadness’s now and again. Knowing about her sad death really cements these feelings in the poems as we can see that unfortunately she gave up, she never found the hope or person she as looking for to save her from her tormented mind. Therefore, with her ruthless verity, it is obvious that Plath’s personal poems project her life in an intense and disturbing way because in the end, this magnificent, poignant poet could see nothing to live for.

Consequences of the Conquest of the Aztecs

In 1519, conquistador Hernan Cortes landed on Mexicos Gulf coast and began an audacious conquest of the mighty Aztec Empire. By August of 1521, the glorious city of Tenochtitlan was in ruins. The Aztec lands were renamed New Spain and the colonization process began. Conquistadors were replaced by bureaucrats and colonial officials, and Mexico would be a Spanish colony until it began its fight for independence in 1810. Cortes defeat of the Aztec Empire had many ramifications, not the least of which was the eventual creation of the nation we know as Mexico. Here are some of the many consequences of the Spanish conquest of the Aztecs and their lands. It Sparked a Wave of Conquests Cortes sent his first shipment of Aztec gold back to Spain in 1520, and from that moment, the gold rush was on. Thousands of adventurous young Europeans - not only Spanish - heard tales of the great riches of the Aztec Empire and they set out to make their fortune just like Cortes had. Some of them arrived in time to join Cortes, but most of them did not. Mexico and the Caribbean soon filled with desperate, ruthless soldiers looking to take part in the next great conquest. Conquistador armies scoured the New World for wealthy cities to loot. Some were successful, like Francisco Pizarros conquest of the Inca Empire in western South America, but most were failures, like Panfilo de Narvaez disastrous expedition to Florida in which all but four men out of over three hundred died. In South America, the legend of El Dorado - a lost city ruled by a king who covered himself in gold - persisted into the nineteenth century.  Ã‚  Ã‚   The Population of the New World was Decimated The Spanish Conquistadors came armed with cannons, crossbows, lances, fine Toledo swords and firearms, none of which had ever been seen by native warriors before. The native cultures of the New World were warlike and tended to fight first and ask questions later, so there was much conflict and many natives were killed in battle. Others were enslaved, driven from their homes, or forced to endure starvation and rapine. Far worse than the violence inflicted by the conquistadors was the horror of smallpox. The disease arrived on the shores of Mexico with one of the members of Panfilo de Narvaez army in 1520 and soon spread; it even reached the Inca Empire in South America by 1527. The disease killed hundreds of millions in Mexico alone: its impossible to know specific numbers, but by some estimates, smallpox wiped out between 25% and 50% of the population of the Aztec Empire. It Led to Cultural Genocide In the Mesoamerican world, when one culture conquered another - which happened frequently - the winners imposed their gods upon the losers, but not to the exclusion of their original gods. The vanquished culture kept their temples and their gods, and often welcomed the new deities, on the grounds that their followers victory had proven them strong. These same native cultures were shocked to discover that the Spanish did not believe the same way. Conquistadors routinely destroyed temples inhabited by devils and told the natives that their god was the only one and that to worship their traditional deities was heresy. Later, Catholic priests arrived and began burning native codices by the thousands. These native books were a treasure trove of cultural information and history, and tragically only a few battered examples survive today. It Brought Forth the Vile Encomienda System After the successful conquest of the Aztecs, Hernan Cortes and subsequent colonial bureaucrats were faced with two problems. The first was how to reward the blood-soaked conquistadors who had taken the land (and who had been badly cheated out of their shares of the gold by Cortes). The second was how to rule large swaths of conquered land. They decided to kill two birds with one stone by implementing the encomienda system. The Spanish verb encomendar means to entrust and the system worked like this: a conquistador or bureaucrat was entrusted with vast lands and the natives living on them. The encomendero was responsible for the safety, education and religious well-being of the men and women on his land, and in exchange, they paid him with goods, food, labor, etc. The system was implemented in subsequent conquests, including Central America and Peru. In reality, the encomienda system was thinly-disguised slavery and millions died in unspeakable conditions, particularly in mines. The N ew Laws of 1542 tried to rein in the worst aspects of the system, but they were so unpopular with colonists that Spanish landowners in Peru went into open rebellion. It made Spain a World Power Before 1492, what we call Spain was a collection of feudal Christian Kingdoms which could barely put aside their own squabbling long enough to oust the Moors from Southern Spain. One hundred years later, a united Spain was a European powerhouse. Some of that had to do with a series of efficient rulers, but much was because of the great wealth flowing into Spain from its New World holdings. Although much of the original gold looted from the Aztec Empire was lost to shipwrecks or pirates, rich silver mines were discovered in Mexico and later in Peru. This wealth made Spain a world power and involved them in wars and conquests around the globe. The tons of silver, much of which was made into the famous pieces of eight, would encourage Spains Siglo de Oro or golden century which saw great contributions in art, architecture, music, and literature from Spanish artists.   Sources: Levy, Buddy. . New York: Bantam, 2008. Silverberg, Robert. The Golden Dream: Seekers of El Dorado. Athens: the Ohio University Press, 1985. Thomas, Hugh. . New York: Touchstone, 1993.