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How information can improve the quality of decision making. 4.1.4 Validation & Verification. Starter: Exam Question. There are a number of ways in which data errors can occur. By giving an example in each case, describe how errors can occur during: (a) Input (2) ( b ) Transcription (2)
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How information can improve the quality of decision making 4.1.4 Validation & Verification
Starter: Exam Question There are a number of ways in which data errors can occur. By giving an example in each case, describe how errors can occur during: (a) Input (2) (b) Transcription (2) (c) Processing (2) (d) Transmission (2)
Define: Validation The process which ensures that data accepted for processing is sensible and reasonable. Verification Checks that the data being typed in matches exactly the data on the document used to supply the information
Main: Verification • Verification means “checking that the data being entered into the ICT system perfectly matches the source of the data.” • E.g. If details form an order form were being typed in using a keyboard, then when the user has finished, the data on the form on the screen will be identical to that on the paper form. Three methods of verification: - Proof reading - Double entry of data - Sending back printouts
Main: Verification - Proof Reading Proof reading involves one user carefully reading what they have typed in and comparing it with what is on the data source (order forms, application forms, invoices etc.) for any errors, which can be corrected. Example entering pupil details into a school database. The information will be provided on a form and then keyed into the database. Typing mistakes are easily made so once the person has finished inputting the information they will work through each field and check with the form that the information is correct.
Main: Verification - Double entry of data Double entry of data is where two people use the same data source to enter the details into the ICT system and only if the two sets of data are identical, will they be accepted for processing. Disadvantage? The cost of data entry is doubled. Example passwords are often keyed in twice when created, only if both versions match will they be accepted. Why? (if a user makes a mistake with a single password they would not know what it was and this would cause unnecessary calls to the helpdesk).
Main: Verification - Sending back printouts Sending back printouts is another way to check that information is correct by printing the information out and sending I back in hard copy from the person who supplied it, in the hope that they will be able to spot anything that is wrong. Example When you book a holiday over the phone the travel agent will send you a printout of the confirmation of the booking for you to check for mistakes. Or if booked online you will be emailed confirmation and the details.
Main: Verifying & Validating content If you are developing a ICT solution to a client problem, there are many ways of checking content so that the final solution is accurate and fit for purpose. WHAT IS CONTENT? The content can be checked by… • Checking the accuracy of content supplied. • Checking the readability of the content based on the characteristics of the user such as age, ICT experience etc. • Spellchecking • Grammar checking • Checking all content is complete • Ensuring that there is no duplication of content • Checking consistency of layout • Checking images • Checking that the font/font size are appropriate for the characteristics of the user • Checking that images are suitable for the text
Main: Verifying & Validating content Accuracy Readability Spell check Grammar check Complete No duplication Consistency Images Font/font size Suitable Make a word out of the first letter of each to help remember all 10
Main: Verifying & Validating content Exam Tip The terms verification and validation often get mixed up. Stress that verification is simply to ensure that no errors have been introduced during data capture. Checking that the details being input match exactly the details on a form such as an application form, order form etc. Validation is a check performed by a computer program. Come up with a way to remember each of them?
Main: Creating Validation Checks When you create an ‘ICT Solution’ other users may not be as careful as you when entering data. You should try to restrict as much as possible the data that a user can enter by using validation checks.
Main: Validation and Databases • When creating databases validation rules are created for some of the fields. • You can specify the type of data that can go into each field and the length. • A message should also be created to appear if invalid data is entered. • Validation checks are also known as Validation Expressions.
Activity: Validating Cells Work through the Validating cells and creating validation messages activity. Validation message The message the user will see if they type in data that does not meet the validation rules for the field. Validation expression/rule The command that a developer must type in order to set up the validation for a particular field/cell.
Plenary: Quiz http://www.teach-ict.com/as_a2_ict_new/ocr/AS_G061/311_data_info_knowledge/validation_verification/quiz/fling_val_ver.htm
Extra: Exam Questions 2. If inaccurate data is processed, it can have a number of different consequences. Describe three distinctly different consequences of processing data that is incorrect. (6) 3. Think about the types of mistake you make when typing information into a computer. Write a list of three different mistakes you can make. (3) 4. A computer manager says ‘data can be valid yet be incorrect’. By giving one suitable examples, explain what this statement means. (3)
