Approaches to Data Cleaning

Approaches to Data Cleaning Data Cleaning approaches: generally, data cleaning contains several steps Data Analysis: A detailed analysis is required to check what type of inconsistencies and errors are to be resolved. An analysis program should be used along with manual analysis of data to identify data quality problems and to extract metadata. Characterization of mapping rules and transformation workflow: We might have to execute a great amount of data cleaning and transformation steps depending upon the degree of dirtiness of data, the amount of data sources and their level of heterogeneity. In some cases schema transformation is required to map sources to a common data model for data warehouse, usually relational model is utilized. Initial data cleaning phases organize data for integration and fix single –source instant complications. Further phases deal with data/schema integration and resolving multi-source glitches, e.g., redundancies. Workflow that states the ETL processes should specify the control and data flow of the cleaning steps for data warehouse. The schema associated data conversions and the cleaning steps should be quantified by a declarative query and mapping language to the extent possible, to allow auto generation of the conversion program. Along with it there should be a possibility to call user written program and special tools during the process of data transformation and cleaning process. A user opinion is required for data transformation for whom there is no built in cleaning logic. Verification: The accuracy and efficiency of a conversion process and transformation designs should be verified and assessed on a sample data to improve the definitions. Repetition of the verification, design and analysis phases may be required because some faults may appear after performing some conversions. Transformation: Implementation of the transformation phase either by running the ETL process for refreshing and loading a data warehouse or during returning queries from heterogeneous sources. Reverse flow of transformed data: once the single source problems are resolved the transformed data should be overwritten in the base source so that we can provide legacy programs cleaned data and to escape repeating of the transformation process for future data withdrawals. For the data warehousing, the cleaned data is presented from the data staging area. The transformation phase requires a huge volume of metadata, such as, workflow definitions, transformation mappings, instance-level data characteristics, schemas etc. For reliability, tractability and reusability, this metadata should be kept in a DBMS-based repository. For example the consequent table Customers holds the columns C_ID and C_no, permitting anyone to track the base records. In the next sections we have elaborated in more detail probable methodologies for data examination, conversion definition and conflict determination. Along with it there should be a possibility to call user written program and special tools during the process of data transformation and cleaning process. A user opinion is required for data transformation for whom there is no built in cleaning logic. The accuracy and efficiency of a conversion process and transformation designs should be verified and assessed on a samp le data to improve the definitions. Repetition of the verification, design and analysis phases may be required because some faults may appear after performing some conversions. Transformation: Implementation of the transformation phase either by running the ETL process for refreshing and loading a data warehouse or during returning queries from heterogeneous sources. Reverse flow of transformed data: once the single source problems are resolved the transformed data should be overwritten in the base source so that we can provide legacy programs cleaned data and to escape repeating of the transformation process for future data withdrawals. For the data warehousing, the cleaned data is presented from the data staging area. The transformation phase requires a huge volume of metadata, such as, workflow definitions, transformation mappings, instance-level data characteristics, schemas etc. For reliability, tractability and reusability, this metadata should be kept in a DBMS-based reposito ry. To maintain data excellence, thorough data about the transformation phase is to be stored, both in the in the transformed occurrences and repository , in precise information about the extensiveness and brilliance of source data and extraction information about the source of transformed entities and the transformation applied on them. For example the consequent table Customers holds the columns C_ID and C_no, permitting anyone to track the base records. In the next sections we have elaborated in more detail probable methodologies for data examination, conversion definition and conflict determination. DATA ANALYSIS Metadata mirrored in schemas is usually inadequate to evaluate the data integrity of a source, particularly if only a small number of integrity constraints are imposed. It is therefore necessary to examine the original instances to get actual metadata on infrequent value patterns or data features. This metadata assists searching data quality faults. Furthermore, it can efficiently subsidize to recognize attribute correspondences among base schemas (schema matching), based on which automatic data conversions can be developed. There are two associated methods for data analysis, data mining and data profiling. Data mining assists in determining particular data forms in huge data sets, e.g., relationships among numerous attributes. The focus of descriptive data mining includes sequence detection, association detection, summarization and clustering. Integrity constraints between attributes like user defined business rules and functional dependencies can be identified, which could be utilized to fill empty fields, resolve illegitimate data and to detect redundant archives throughout data sources e.g. a relationship rule with great certainty can suggest data quality troubles in entities breaching this rule. So a certainty of 99% for rule â€Å"tota_price=total_quantity*price_per_unit† suggests that 1% of the archives do not fulfill requirement and might require closer inspection. Data profiling concentrates on the instance investigation of single property. It provides information like discrete values, value range, length, data type and their uniqueness, variance, frequency, occurrence of null values, typical string pattern (e.g., for address), etc., specifying an precise sight of numerous quality features of the attribute. Table3. Examples for the use of reengineered metadata to address data quality problems Defining data transformations The data conversion phase usually comprises of numerous steps where every step may perform schema and instance associated conversions (mappings). To allow a data conversion and cleaning process to produce transformation instructions and therefore decrease the volume of manual programming it is compulsory to state the mandatory conversions in a suitable language, e.g., assisted by a graphical user interface. Many ETL tools support this functionality by assisting proprietary instruction languages. A more common and stretchy method is the use of the SQL standard query language to accomplish the data transformations and use the chance of application specific language extensions, in certain user defined functions (UDFs) are supported in SQL:99 . UDFs can be executed in SQL or any programming language with implanted SQL statements. They permit applying a extensive variety of data conversions and support easy use for diverse conversion and query processing tasks. Additionally, their impleme ntation by the DBMS can decrease data access cost and thus increase performance. Finally, UDFs are part of the SQL:99 standard and should (ultimately) be movable across many stages and DBMSs. The conversion states a view on which additional mappings can be carried out. The transformation implements a schema rearrangement with added attributes in the view achieved by dividing the address and name attributes of the source. The mandatory data extractions are achieved by User defined functions. The U.D.F executions can encompass cleaning logic, e.g., to eliminate spelling mistakes in city or deliver misplaced names. U.D.F might apply a significant implementation energy and do not assist all essential schema conversions. In specific, common and often required methods such as attribute dividing or uniting are not generally assisted but often needed to be re-applied in application particular differences. More difficult schema rearrangements (e.g., unfolding and folding of attributes) are not reinforced at all. Conflict Resolution: A number of conversion phases have to be identified and performed to solve the numerous schema and instance level data quality glitches that are mirrored in the data sources. Numerous types of alterations are to be executed on the discrete data sources to deal with single-source errors and to formulate for integration with other sources. Along with possible schema translation, these preliminary steps usually comprises of following steps: Getting data from free form attributes: Free form attributes mostly take numerous discrete values that should be obtained to attain a detailed picture and assist additional transformation steps such as looking for matching instance and redundant elimination. Common examples are address and name fields. Essential transformations in this phase are reorganization of data inside a field to comply with word reversals, and data extraction for attribute piercing. Authentication and alteration: This step investigates every source instance for data-entry mistakes and attempts to resolve them automatically as much as possible. Spell-checking built on dictionary searching is beneficial for finding and adjusting spelling mistakes. Additionally, dictionaries on zip codes and geographical names assist to fix address data. Attribute reliance (total price – unit price / quantity, birth date-age, city – zip area code,†¦) can be used to identify mistakes and fill missing data or resolve incorrect values. Standardization: To assist instance integration and matching, attribute data should be changed to a reliable and identical form. For example, time and date records should be transformed into a defined form; names and other string values should be changed to lower case or upper case, etc. Text data might be summarized and combined by stop words, suffixes, executing stemming and removing prefixes. Additionally, encoding structures and abbreviations should continuously be fixed by referring distinctive synonym dictionaries or implementing predefined transformation rules.

Student- Teacher relationships will improve :: essays papers

Student- Teacher relationships will improve From the very first day of school on, student- teacher relationships will be improved in smaller classes. Patricia Handley has been an elementary school teacher for twenty-eight years. She has had the opportunity to teach in both small and large classes. On the first day of teaching her first small class Handley comments, â€Å"I immediately noted their sense of importance; no one seemed lost in the crowd† (2002). In a small class, as the students enter, the teacher can take the time to greet each one. The teacher will learn the names of the children faster. The quicker the student is called by his or her name and the more individual attention they get from the teacher, the more comfortable they are going to feel expressing themselves to the teacher in a learning environment. â€Å" In a class of fifteen students, we can quickly learn about one another and do so in more depth† (Handley, 2002). Each child is an individual. Once a teacher has the chance to get to know the students, they can work to accommodate the strengths and weaknesses in the learning process. Students will have a more worthwhile learning experience Many schools throughout the nation have tried smaller classes. Members of a teaching team in Narcoossee Community School in St. Cloud, Florida have commented that when students come back from summer vacation, they are enthusiastic to see everybody and begin the learning process, more so than before the program started (McGoogan, 2001). Group discussions can be a major part of a school day. In small classes, everybody can have a chance to participate. When students are able to speak to a class in their elementary years, they will gain confidence. If they get used to contributing to class discussions, more than likely, they will hold onto that and use it as they progress through high school and college. When students are in a smaller setting, they will get to know one another better, as well as the teacher. When students are comfortable with the people around them, they will not feel shy or intimidated to raise their hands to answer a question. As students share their ideas and feelings with their peers, they will enhance their learning. They will be able to learn from what others say and they will become more interested on the topic of the discussion if they are involved in some way.

American influence to world war

The First World War or the Great War was primarily a global conflict that was fought in Europe from 1914 to 1918. Some nations were actively involved in this war and among them were Britain and France. All this long America had not being involved in this war . They sought to remain neutral. They had the intentions of being silent both in deeds and thoughts . As a matter of fact, in December 1916 the then president of America Woodrow Wilson had offered himself as a mediator in this European conflict. This idea of being neutral did not go for long following a series of events that were going on between 1915 and 1917.The Americans lost their lives when German submarine warfare declared the â€Å"sinking of ships tradition†. The most hurting was the attack on May 7, 1915 against Lusitanian ship when 128 Americans perished. This broke the relationship between the Americans and Germans. One of the factors that led to joining in this war was President Wilson’s idealism. He per suaded the congress to declare war on Germany . He argued that western civilization could be destroyed or hampered thus his announcement â€Å"war to end wars† This was taken to mean that his intention was to create a ground for peace building and prevention of catastrophic future wars.According to Wilson, the way out to resolving these disputes could only be attributed to issues like ,general association by nations that would form international associations of nations to preach peace for example the league of nations, The Turkish People of Ottoman empire were to become a sovereign. He also looked forward to seeing integrity being granted to Romania, Montenegro, Serbia and Balkan states at the same time Serbia to be given the freedom to use the Adriatic Sea. He wanted the freedom to the seas and free trade. The Italian borders were to be redrawn on lines of nationality.Wilson wanted the abolishment of secret treaties . Another key factor for joining the war was the economic i nterests. As these conflicts went on, the Americans were eying on it. It was becoming clear that the British-French alliance was at the verge of loosing the war to the Germans. Their anxiety was attributed to the fact that the Americans were fully involved in financing them. As observed earlier, the turning point for waging war on the Germans was when they declared the â€Å"unrestricted warfare on submarines† in January 1917. The trading business ties between the Americans and other central powers had a negative impact.It was at this point that Americans declared war but there was nothing to do with naval policy as perceived to be. It was about the safe guarding of their economic investment and trade rather than protecting the poor Americans. In another perspective, due to Americans neutral stand, their businessmen were in a position to trade with both sides and got large profits. They were trading with both the Germans and other super powers like the British and French. (Vi ncent Joseph 2003) As the war went on and continued the private European business and the British government and its allies bought more and more American weapons and non-military goods.To pay for them, they had to borrow money from American financiers since they had exhausted their resources. This made them earn lots of wealth. Before the World War 1, majority of the American exports went overseas in foreign ships. Unfortunatery when British entered into war, the British navy blocked German ships from conducting and engaging in international trade. The German Navy also halted the British and allied from shipping. This resulted to decrease in the number of ships available for freight and consequently increase in cost of shipping goods.This made American exporters find it difficult to conduct their business as usual . They reiterated by joining the war with an aim of ending this stalemate. (Allan R Millet2001) America was also influenced to join the war against the Germans by pressure from domestic propaganda campaigns. This was executed by a committee on public information. These propagandas were being conducted by many government committee community leaders who were giving pro-war speeches in many public gatherings. There were private and government vigilante groups that were involved like; the American Protective League.There was a general harassment and repression on those opposed to Americans joining the war. There were also other forms and means of propagating propaganda and among them were; large print posters, photos, newsreels, magazines and newspapers among other methods. Americans were also influenced to join in the war due to the issue of German Naval policy. In 1917 Germany returned to the policy of unrestricted warfare on submarine. This policy was first introduced in 1915. This naval policy declared the area in the British Isles a war zone.This meant that the ships trading along these waters and those of neutral states would be attacked by the nav al. There were chains of attacks on ships that led to the sinking of the British ship,Lusitania by a German U_boat. Despite the fact that this ship was carrying military equipment and was rather meant for passengers only did not hider the then president of America Woodrow Wilson to declare war on Germany in 1917(Allan R Millet ,2001) In conclusion, the German Naval policy stipulated that, whenever an American ship was found on the Atlantic Ocean and be suspected to be providing military equipment to the British would be destroyed.The economic interest of the American was to open the trade-links especially in Europe. However, this could not happen because the German U-boats were destroying ships including the Lusitanian which made America join the war. Work cited Allan R Millet, Military effectiveness in First World War, Oxford University Press. (2001) Albert Edward, McKinley World War I McKinley Publishers, London (2002) Vincent Joseph, A concise History of World War I, Oxford Unive rsity Press, London, (2003).

whats good without evil Essay - 1219 Words

Without Evil What’s Good nbsp;nbsp;nbsp;nbsp;nbsp;â€Å"If my devils are to leave me, I am afraid my angels will take flight as well.† Rainer Maria Rilke wrote this to explain the nature of humanity. He expressed his views on human behavior and how humans think. Without evil, one does not know exactly what goodness is. Everyone possesses good and evil qualities. For they are balanced and create stability in everyone. If the one doesn’t exist then humans would not be able to differentiate or comprehend whether their actions are right or wrong. In our nature life always presents two sides of a situation therefore, making us act and think the way we do every day. nbsp;nbsp;nbsp;nbsp;nbsp;In the beginning of the novel Lord of the†¦show more content†¦They seemed to speak his language, although he didn’t understand why they didn’t understand him. Grendel wants to be friends with the men, although being a descendent of Cain, he decides to attack the mead hall instead. His evil monster side was that he wanted to kill and destroy the humans. He felt guilty at first when he did this, but discovered this is what he was meant to do to these people. When Grendel killed a man he knew it was bad because he had that good quality within him. The Dragon, who told Grendel that he was born a monster and therefore must be the monster and kill, influenced Grendel’s evil side. Whether the men were nice or not it was his destiny to be a monster. He wanted to be good, although he felt he needed to be evil. One needs both qualities in order to distinguish between them. nbsp;nbsp;nbsp;nbsp;nbsp;In contrasting views, there could be two different ideas symbolizing the nature of humans. The two poems by William Blake, â€Å"The Lamb† and â€Å"The Tyger†, represent the dual nature of humanity. â€Å"The Lamb,† although a simple poem, has a very deep meaning. For instance, the â€Å"lamb† shows innocence with words such as â€Å"delight†, â€Å"child†, and â€Å"tender voice†. The lamb is compared to an angelic figure. On the other hand, â€Å"The Tyger,† is expressed to be devilish with words such as â€Å"fire†, â€Å"hammer†, â€Å"chain†, and â€Å"furnace†. The Tyger asked God, â€Å"Did he who made theShow MoreRelatedMr. L. Mackie s Evil And Omnipotence1718 Words   |  7 Pages L. Mackie’s â€Å"Evil and Omnipotence† criticizes the argument that God exists by showing that religious beliefs are positively irrational and that parts of the essential t heological doctrine are inconsistent with one another. The problem of evil is one of the oldest problems in philosophy. The problem of evil is a logical problem for only the people who believe that there is a God who is both (1) omnipotent and (2) wholly good; yet (3) evil exists in the world. 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