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Data and Information

Data and Information. Data and Information . Differences between data and information Data collection and data preparation Sources of error, data validity and data control Processing data, including search, sorting, merging

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Data and Information

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  1. Data and Information

  2. Data and Information • Differences between data and information • Data collection and data preparation • Sources of error, data validity and data control • Processing data, including search, sorting, merging • Processing information, including re-organization, conversion, communication. • Batch processing versus real-time processing

  3. Binary, denary and hexadecimal numbers • Bit and byte • American standard code for information interchange (ASCII) • Representation of Chinese characters

  4. Differences between data and information • What is the difference between data and information? • Data is a collection of raw facts that are not organized and has no meaning on its own. • Information is data that has been organized. It is meaningful and useful for decision making.

  5. Data collection and data preparation

  6. Data input • Discuss with your classmates, write down some examples of errors caused by manual input.

  7. Data input and sources of error

  8. Sources of error, data validity and data control • Data validation • Comparing data with a set of rules or values • Make sure data is reasonable and valid • Discuss and give some examples of validity check

  9. Field presence check • Field length check • Range check • Format check • Check digit

  10. Guess what kind of validity checks are used

  11. Data verification • Data verification is a control to check if the input data matches the source document. • Input data twice • Double data entry

  12. Data structure A collection of related data files = Database Field Record

  13. A database is a group of tables

  14. Key Field • Key field / primary key • unique • Identify the target record

  15. Processing data, including search, sorting, merging • Sorting : • to organize a list of records in a specific order • Sort key

  16. Searching • To retrieve a specific record of data from database • Sequential search, Binary search (More to learn in Programming) Name = Chu SW

  17. Merging Data • Merge two tables of records into a new table

  18. A secondary school uses a computer system, called EasyMark, for handling the examination marks of students. The system consists of two modules: AVE and ORDER. AVE is responsible for computing the average mark for a student. ORDER is responsible for arranging the students of a given class in the descending order of their average marks.

  19. Describe the input data and the output information of the modules AVE and ORDER respectively. (4 marks) Input data (AVE): • The different examination marks of a student Output information (AVE): • The average mark of a student Input data (ORDER): • The average mark of each student Output information (ORDER): • The list of students arranged from the one getting the highest average mark to the one getting the lowest average mark.

  20. Suggest two additional features to enhance the functionality of EasyMark. (2 marks) A module to find out which subjects are passed and failed for each student. A module to find out the grade of each subject for each student. A module to find out the order of the marks of a specific subject for all students.

  21. The school has 25 classes, 900 students in total, and each student has to take 8 subjects. Suppose EasyMark stores the students’ marks in a table, in the following format of a record: • How many records are there in the table? (2 marks) • State one problem in the use of this table and suggest one way of fixing it. (2 marks) (HKCEE CIT 2005)

  22. c) Number of records: 900x8 = 7200 records d) The computer system cannot distinguish the students having the same name in the same class. To fix the problem, a key field which is unique for each student should be added.

  23. Quiz • Ch2 (2.1 – 2.3.1) • 2/12/2008

  24. Processing information, including re-organization, conversion, communication. • What is re-organization? • It includes presenting the information with different structures or manipulating the information from existing records. • Why? • This is because not all structures are equally ready for use or suitable for specific needs.

  25. Filtering and sorting • Statistic calculations

  26. Example Filtering Sorting

  27. Statistic calculation e.g. : calculating the passing rate of the test

  28. Processing information, including re-organization, conversion, communication. • Conversion of Information • e.g: Grading system • Why? • It is more efficient to manipulate numeric data than character representations.

  29. Processing information, including re-organization, conversion, communication. • Communication of information • Exchange information between two different systems. • e.g. : • http (Hypertext Transfer Protocol) • ftp (File Transfer Protocol) • telnet (Telnet Remote Protocol)

  30. Quiz • Ch2 (2.1 – 2.3.3) • 2/12/2008

  31. Assessment • Unit Tests: 15% • Assignments: 15 % • Mid-term Test: 20% • Exam: 50%

  32. Assignment • Total marks: 100 • Report + CD (The program) • Deadline: 2nd Jan, 2009 • Late of submission: 20% off for each day!! • Bonus: +10 marks on or before 19th Dec, 2008

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