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Cambridge IGCSE0417

Software tools

Information Communication Technology 0417 Chapter Notes

What this chapter covers

Software toolsProofing techniques
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Software tools notes

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In this chapter

  1. 1Reducing errors with software tools
  2. 2How a spell checker finds errors
  3. 3When spell check gets it wrong
  4. 4What validation does and does not do
  5. 5Range, length and format checks
  6. 6Presence, character and type checks
  7. 7Setting a validation rule in a spreadsheet
  8. 8Visual verification of data entry
  9. 9Proofreading a document
  10. 10Verification and double data entry
  11. 11Why validation as well as verification

1. Reducing errors with software tools

Automated tools such as spell check and grammar check help make sure that all work produced contains as few errors as possible. Make the changes that are appropriate.

Validation routines reduce errors at the point of data entry. They are the other tool in this note.

The purpose of spell check is to identify data entry errors and help the user reduce them. Do not answer "to check spelling of words".

Examiner insight

“The explanation of the purpose of spell check software usually lacked detail and responses such as ‘to check spelling of words’ or ‘to correct errors’ were often given without recognising that the purpose is to identify data entry errors and assist the user in reducing errors.” “Several responses included details about checking and correcting grammar which was not relevant to the question.”

Worked example 12 marks

Explain the purpose of spell check software.

  1. 1

    It is used to identify data entry errors. [1]

  2. 2

    It assists the user in reducing errors in the work. [1]

2. How a spell checker finds errors

A spell checker reads each word in the document. It compares each word with the words stored in its dictionary.

A word that does not appear in the dictionary is marked, and the software offers suggestions. It does not correct the word automatically: the user decides.

Describe this comparison, not just what you see on the screen.

Examiner insight

“Candidates wrote about what they saw happening when a spell checker is used, rather than how the spell checker determines which words are incorrectly spelt.” “The correct answer was a comparison of each word with words stored in the dictionary.”

Worked example 12 marks

Describe how a spell checker finds a word that may be spelt wrongly.

  1. 1

    Each word is read and compared ... [1]

  2. 2

    ... with the words stored in the dictionary. [1]

3. When spell check gets it wrong

Automated suggestions from spell check software do not always give the correct response. The user must decide whether to accept each one.

A proper noun, such as a name, may be spelt correctly but is not recognised by the dictionary. The same happens when the text is in another language from the one the checker uses. The dictionary is also limited in size.

Examiner insight

“Candidates should make appropriate use of the spell checker and proofing tools available and understand that automated suggestions given by spell check software may not always be appropriate.” “There were many correct answers mentioning that proper nouns might be spelled correctly but not recognised by the dictionary.”

Worked example 12 marks

A pupil types her friend's name, Okonkwo, in a letter. The spell checker underlines it. Give two reasons why this may happen.

  1. 1

    A name is a proper noun, which may not be in the dictionary. [1]

  2. 2

    The checker may be set to a different language from the name. [1]

4. What validation does and does not do

Validation checks that data is reasonable and follows the set criteria.

Data that passes validation can still be wrong. Validation and verification reduce errors, they do not eliminate them.

Validation is not proofreading, and it is not re-reading the document.

Examiner insight

“Validation checks if data is reasonable and follows the set criteria. Both are used to reduce errors do not eliminate them.” “Some candidates thought that validation involved re-reading the document or checking that it was 100% correct.”

Worked example 12 marks

A student says that a validation check makes sure all the data entered is correct. Explain why the student is wrong.

  1. 1

    Validation only checks that the data is reasonable and follows the set criteria. [1]

  2. 2

    Data can pass the check and still be wrong. A mark of 40 typed instead of 4 is reasonable, so it is accepted. [1]

5. Range, length and format checks

A range check accepts only data between a lowest and a highest value.

A length check accepts only the stated number of characters. It is often an exact number, and a space counts as a character.

A format check accepts only data in a set pattern, such as `dd/mm/yyyy`. Describe the rule. Do not just write down a value from the table.

Examiner insight

“For those that gave the correct validation check many were vague with the description, for example Length check, the description was checking that up to 4 characters when the actual answer is exactly 4 characters or format check and then writing down dd/mm/yy rather than dd/mm/yyyy.” “In the length check many candidates missed the space and therefore lost a mark.”

Worked example 14 marks

A form has a field Form_code that must always hold exactly 4 characters and a field Mark that must be from 0 to 100. Name and describe a suitable validation check for each field.

  1. 1

    Form_code: length check. [1]

  2. 2

    It accepts only data with exactly 4 characters. [1]

  3. 3

    Mark: range check. [1]

  4. 4

    It accepts only a mark from the lowest value 0 to the highest value 100. [1]

6. Presence, character and type checks

A presence check makes sure that something has been entered. It only suits a field that cannot be empty.

A character check accepts only characters of the allowed kind, such as letters in a name field. A type check accepts only the stated type of data, such as a number.

Name the check. Do not answer with the name of a data type.

Examiner insight

“Some candidates gave presence check, a presence check only works where the field cannot be empty, this field could be empty as it was not a key field.” “Many candidates incorrectly answered with data types rather than validation checks.”

Worked example 12 marks

A library records the Date_book_sold only when a book is sold. Explain why a presence check is not suitable for this field.

  1. 1

    A presence check only works where the field cannot be empty. [1]

  2. 2

    A book may not have been sold yet, so the field can be empty. [1]

7. Setting a validation rule in a spreadsheet

To restrict entry, select the cell and open the data validation tool. Choose what to allow, then enter the rule.

For a fixed list of answers, set the criteria to List. Type the items with the capitals the question gives. Do not put "and" or "or" in the source.

Where the items are already in a table, enter the cell range of that list rather than typing the items again. For a number with a decimal part, allow decimal, not whole number. Evidence of the rule must show the cell it is applied to.

Examiner insight

“Some candidates did not set the criteria to ‘List’ and some included ‘and’ or ‘or’ in the source.” “Some candidates did not set the validation criteria to decimal.”

Worked example 14 marks

Cell B12 must accept only the text Yes or No. Describe how to set a validation rule for this cell.

  1. 1

    Select cell B12 and open the data validation tool. [1]

  2. 2

    Set the criteria to List. [1]

  3. 3

    Type the source as `Yes,No`, with no "and" or "or" between the items. [1]

  4. 4

    Use the capitals given in the question: `Yes` and `No`, not `yes` and `no`. [1]

Recap

  • Spell check identifies data entry errors and assists the user in reducing errors.
  • A spell checker compares each word with the words stored in its dictionary.
  • Suggestions are not always correct. Names and other languages are not recognised.
  • Validation checks that data is reasonable and follows the set criteria. It does not prove the data is correct.
  • Range check: between limits. Length check: the stated number of characters. Format check: a set pattern.
  • Presence check only suits a field that cannot be empty. Name the check, not a data type.
  • In a spreadsheet, a List rule uses the capitals in the question and no "and" or "or".

8. Visual verification of data entry

Visual verification compares the data entered with the source document. It checks that the data has been copied correctly. Proofreading does not need a source document.

Identify and correct data entry errors: transposed numbers, incorrect spelling, inconsistent character spacing and inconsistent case. Use the spell checker, but check each suggestion: a suggested change to a company name may not be appropriate.

Examiner insight

“Some candidates stated that visual verification checked that the data was correct when in fact it checks that the data has been copied correctly.” “The software spellcheck tools were not always used appropriately with changes made to company names in the table that should have been retained.”

Worked example 12 marks

A clerk copies the product code KT-4821 from a paper form. The screen has KT-4281. Name this type of error and state how visual verification finds it.

  1. 1

    transposed numbers: the 8 and the 2 have swapped places [1]

  2. 2

    the data on the screen is compared with the source document, the paper form [1]

9. Proofreading a document

Proofread the layout and presentation as well as the spelling. Correct inconsistent line spacing and inconsistent or incorrect application of styles. Leave pre-applied styles unchanged.

Remove blank pages or slides. Remove widows and orphans: a single line of text or a subheading left at the top or bottom of a column or page. Make sure a table or list is not split over columns or pages.

Examiner insight

“Good proofreading skills were not always evident as widows/orphans were not controlled and the columns did not always align at the top of the page.” “Some candidates incorrectly made changes to the formatting of the EX-body style in the recall text with justification, linespacing and paragraph spacing often changed for one or more paragraphs.”

Worked example 12 marks

Spell check and proofread the document. Make sure that: the table and list are not split over columns or pages; there are no widows or orphans; there are no blank pages; the original DB-body and DB-table styles are maintained; spacing is consistent between all items.

  1. 1

    two spelling errors corrected [1]

  2. 2

    document complete, pages and columns aligned at the top, no widows or orphans, list and table not split, no blank pages, pre-applied styles unchanged with consistent spacing [1]

10. Verification and double data entry

Verification checks that data has been correctly copied from a source document. It reduces data entry errors. It does not check that the data is correct.

The two methods are visual checking and double data entry.

In double data entry the data is entered twice, by two people. The computer then compares the two versions.

Examiner insight

“An explanation of double data entry was allowed but some candidates simply repeated the name by stating that data was entered twice without adding by two people.” “As in previous sessions some candidates still write that it is to check that the data entered is correct or relate it back to proof reading.”

Worked example 12 marks

Describe how double data entry is carried out.

  1. 1

    the data is entered twice, by two people [1]

  2. 2

    the computer compares the two versions [1]

11. Why validation as well as verification

Verification only checks that the data is copied correctly. The source may be incorrect, so data that matches the source can still be wrong.

Validation checks that the data is reasonable and follows the set criteria.

Both are needed. Both reduce errors but do not eliminate them: neither check, nor both together, proves that the data entered is correct.

Examiner insight

“Some candidates wrote that verification is used to show if data is correct, this is not the case as it only checks if data is copied correctly as the source may be incorrect.”

Worked example 12 marks

A school office types exam marks out of 100 into a database from paper mark sheets. Explain why it uses validation as well as verification.

  1. 1

    verification only checks the marks are copied correctly from the mark sheet, and the mark sheet may be incorrect [1]

  2. 2

    validation checks each mark is reasonable, so a mark of 150 is rejected [1]

Recap

  • Visual verification: compare the data entered with the source document and correct data entry errors.
  • Look for transposed numbers, incorrect spelling, inconsistent character spacing and inconsistent case.
  • Proofread: consistent spacing and styles, no blank pages or slides, no widows or orphans, no split table or list.
  • Verification checks data is correctly copied from the source, not that it is correct.
  • Double data entry: entered twice by two people, then the computer compares the two versions.
  • Validation checks data is reasonable. Both are needed, and both only reduce errors.

End-of-chapter exercise

Test yourself on the whole chapter. Work through these before moving on.

  1. Name the part of a spell checker that holds the words each typed word is compared with.1 mark
  2. Describe how a spell checker decides that a word may be wrong.2 marks
  3. A pupil types the name Wanjiru Mbugua in a report. The spell checker underlines both words. Give a reason and say what the pupil should do.2 marks
  4. A cell holds the weight of a parcel in kg, for example 2.5. A validation rule is to be set on the cell. State the type of data to allow and why whole number would be wrong.2 marks
  5. An office worker accepts every suggestion made by the spell checker without reading it. Explain why this is a risk.2 marks
  6. Define validation.2 marks
  7. A field must hold exactly 6 characters. A user types KT 417. Does it pass a length check? Give a reason.2 marks
  8. A form needs the date in the format dd/mm/yyyy. A user types 07-03-2026. A length check of exactly 10 characters accepts it. Name the check that rejects it and describe how the check works.3 marks
  9. A bicycle hire shop gives every bike a Bike_code of two letters, a space and four digits, such as BK 0417. (a) Describe a length check for Bike_code. (b) Three codes are typed: BK0417, BK 04A7 and BK 0471. State which of them the length check rejects and give a reason. (c) Name and describe a check that rejects BK 04A7.5 marks
  10. A beekeeping club records each hive inspection. The table shows the rule for each field and the validation check a member plans for it. (a) Explain what is wrong with the plan for Hive_ID. (b) Explain what is wrong with the plan for Frames_of_brood. Name and describe the check that should be used. (c) Explain why the plan for Date_honey_taken is not suitable. (d) The plan for Queen_seen accepts the letter X. Name and describe a check that rejects X. (e) A member types 9 for Frames_of_brood when the hive has 6. Explain why validation accepts it. | Field | Rule for the data | Member's plan | | --- | --- | --- | | Hive_ID | one letter then three digits | length check, up to 4 characters | | Frames_of_brood | from 0 to 11 | integer | | Queen_seen | Y or N only | length check, exactly 1 character | | Date_honey_taken | empty until honey is taken | presence check |8 marks
  11. State what is meant by a transposed number error.1 mark
  12. A form has the name Anna Brown. It is typed in a database as "anna Br own". Identify two data entry errors.2 marks
  13. Give two methods of verification.2 marks
  14. A presentation has a slide with no content at the end. A heading on another slide uses a different style from the other headings. State the two proofreading corrections needed.2 marks
  15. A report is set in two columns. A subheading is the last line of the first column and its paragraph starts at the top of the second column. A list starts on page 1 and finishes on page 2. Identify the two layout faults.2 marks
  16. A spell checker suggests changing the company name Brightwell Ltd to Brightwater Ltd. Explain why the suggestion should not be accepted without checking.2 marks
  17. A candidate writes: "Double data entry is when the data is entered twice." This earns no marks. Write a description that earns 2 marks.2 marks
  18. A clerk enters the year of birth 2105 from a form. A second clerk also enters 2105 from the same form. The computer compares the two versions and finds no difference. Explain why validation is also needed.3 marks
  19. A vet writes each animal's mass on a card. A dog has a mass of 32.5 kg, but the vet writes 23.5 kg on its card. A receptionist types 23.5 into a database and then compares the screen with the card. A colleague says: "You have verified it, so the mass is correct." (a) Name the check the receptionist made. [1] (b) Explain why the colleague is wrong. [2] (c) Later the receptionist reads the record through for mistakes without the card. Name this check and state why it is not verification. [1]4 marks
  20. A swimming club accepts members aged 8 to 18. Two volunteers each enter the age from every paper form and the computer compares the two versions. A range check then accepts only ages from 8 to 18. The table gives three forms. (a) For each form, state which check, if any, detects an error. Give a reason each time. [3] (b) The member on form C is really 12. Use the three forms to explain why the club needs both checks, and what the two checks together still cannot do. [3] | Form | Age on form | Volunteer 1 enters | Volunteer 2 enters | | --- | --- | --- | --- | | A | 14 | 14 | 17 | | B | 15 | 51 | 51 | | C | 13 | 13 | 13 |6 marks

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