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
Data input
Data processing
e.g. : sorting, searching, merging and calculating statistics
Information output

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

7. Data input and sources of error
Source of error
Example
Data source error
Data source providers provides incorrect data.
An interviewee reports an incorrect telephone number.
Transcription error
Data is read or typed in incorrectly
‘1’ as ‘l’ or ‘o’ as ‘0’
Transposition error
Two consecutive digits are swapped
Type 61 when you intend to type 16

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 Field Record
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
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. How many records are there in the table? (2 marks)
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)
Class
Name
Subject
Mark

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. What is re-organization?
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. Conversion of Information
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. Communication of information
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