3.1 Data and Information

1. The rapid development of technology exposes us to a lot of facts and figures every day. Some of these facts are not very meaningful to us. We have to process them properly before they become useful for us. Data A collection of unorganized facts and has no meaning on its own In the form of numbers, characters, symbols, audio, graphics or video clips, etc. Information the processed data which has a specific meaning, and it is useful for decision making. 3.1Data and Information

2. 3.1Data and Information Imagery of data (left) and information (right) Process 17 17 16 18 17 167 165 169 177 160 Peter Mary Jeff John May Data Information Data is processed into information.

3. 3.1Data and Information Imagery of data (left) and information (right) Process 17 17 16 18 17 167 165 169 177 160 Peter Mary Jeff John May Data Information Data is processed into information.

4. 3.2Data Processing • Common types of data processing: • Searching • Calculation • Sorting • Deleting • Inserting • Updating

5. 3.2Data Processing Quarterly sales record from January to March

6. Searching Look up specific information from a database based on certain criteria. e.g. If we want to find the sales of ‘Fan’ in January, a possible way is to examine the column ‘Product’ until we see the product name ‘Fan’. When the record is located, the sales of ‘Fan’ in January can be found in the third column ‘January’. 3.2Data Processing

7. Calculation Mathematical manipulation of data to produce other useful information such as total and average. The following shows the formula to calculate the first-quarter total sales and the monthly average sales for each product: first-quarter total sales = sum of sales in January, February and March monthly average sales = first-quarter total sales / 3 3.2Data Processing

8. Calculation 3.2Data Processing Sales record from January to March with the result of calculation

9. Sorting The rearrangement of records, which is a row of a table, according to a specific criterion. e.g. We want to sort the records in a descending order of the average monthly sales. In this case, the average sale is used as the sort key. The value of a sort key is used as a reference in rearranging records in a sorting process. 3.2Data Processing

10. Sorting 3.2Data Processing Sorted sales record

11. Deleting The removal of a record from the table. e.g. The sales record for the ‘Fan’ is known to be taken from a wrong source. The record should be removed from the table. 3.2Data Processing The sales record of ‘Fan’ is deleted.

12. Inserting Adding a new record to the existing table. 3.2Data Processing A sales record ‘Heater’ is inserted.

13. Updating Modifying the data of existing records. e.g. The product code for ‘Cooker’ should be ‘10’. The product code is updated from ‘1’ to ‘10’. 3.2Data Processing A sales record ‘Cooker’ is updated.

14. Updating Modifying the data of existing records. e.g. The product code for ‘Cooker’ should be ‘10’. The product code is updated from ‘1’ to ‘10’. 3.2Data Processing A sales record ‘Cooker’ is updated.

15. 3.3Correctness of Data • The accuracy of the inputted data determines the quality of the output of data processing. • If the data entered is incorrect or incomplete, the program will not generate useful result. This principle is known as garbage-in-garbage out (GIGO). • Two methods used to reduce errors of inputted data: • data validation • data verification

16. 3.3Correctness of Data • Data Validation • The process of checking data with a set of rules or values to make sure that the data entered are reasonable and valid. • This is usually done by the program which validates data in the data entry screen. • Common types of data validation: • Range check • Format check

17. 3.3Correctness of Data Range check Data validation • Range Check • Ensure that the value of inputted data falls within a valid range. • In the above example, the age entered must be between 18 and 55. Format check An example of applying data validation: filling an online registration form

18. 3.3Correctness of Data • Format Check • Ensure that the inputted data is of a certain type or pattern. • In the above example, user ID should consist of alphabets, numbers or a mixture of them.

19. 3.3Correctness of Data • Data Verification • A measure to check whether the inputted data matches with that in the source document • This measure is carried out manually. • Examples: • Confirmation • Inputting data twice

20. 3.3Correctness of Data • Confirmation • Ask users to check manually whether the inputted data is free of error. • e.g. After a user enters data for the creation of a new account, the program will display a confirmation window to display the inputted data. • The user is asked to confirm that the data entered is correct by clicking . Confirm A window displaying entered data for confirmation

21. 3.3Correctness of Data • Inputting Data Twice • Inputting data twice is to ask users to enter the data twice. • The computer system then checks the second entry against the first one. • It reports any discrepancies and the user is required to correct the error manually. Password is entered twice to verify the inputted data.

22. 3.3Correctness of Data • Inputting Data Twice • Inputting data twice is to ask users to enter the data twice. • The computer system then checks the second entry against the first one. • It reports any discrepancies and the user is required to correct the error manually. Password is entered twice to verify the inputted data.

23. 3.4Types of Data Processing • Batch Processing • The computer does not process data immediately after it is entered. • Data and jobs are accumulated. A batch file is created to instruct the computer when and how to carry out the jobs. • The computer processes the accumulated data and jobs as instructed automatically at a specified time.

24. 3.4Types of Data Processing • Batch Processing • Examples: • Print monthly bank statements. • Calculate examination results. • Back up files stored on a server. Monthly bank statements Examination result

25. 3.4Types of Data Processing • Real-time Processing • A mode of operation that the program allows a job to be handled as fast as possible upon request. • Any data entered is immediately processed to produce output, which is then fed back to users. • The response time is short and the information is always updated.

26. 3.4Types of Data Processing • Real-time Processing • Examples: • Online ticketing system • ATM system Online ticketing system ATM system

27. 3.4Types of Data Processing • Real-time Processing • Examples: • Online ticketing system • ATM system Online ticketing system ATM system