INTRODUCTION

There are two major factors that can lead to a computer giving you the incorrect results when you enter data, namely human error and bugs. In this chapter, you will learn about the effect that human error has on data input and the accuracy of data, how data is verified and validated, and what software bugs and hardware failure are and how they can affect your computer.

UNIT
 9.1   Human error

When data is added manually to a spreadsheet or database, there is room for error.

If the user makes a mistake when entering data, the computer will not be able to pick up on that. This is why we verify and validate data before analysing it.

Human errors can have a significant impact on the validity and accuracy of data. If, for example, a scientist makes a calculation mistake with one entry in a spreadsheet, their results could be off by a large degree. These types of errors can also impact businesses. If an employee enters the price of a product into the database incorrectly, the business may lose money.

THE GIGO PRINCIPLE

GIGO is a concept in data capture and evaluation. It stands for “garbage in, garbage out” and the idea is that if you enter bad data into a system (such as a database or Excel spreadsheet), you will get bad results, or bad input will give you bad output.

UNIT
 9.2   Verification and validation of data

DATABASES

As you learned in Term 1, a database is a collection of a large amount of data, which is organised into files called tables.

When discussing data, you need to remember that there are many different types of data. The most common data types, and the ones you are most likely to deal with, are:

• strings
• numeric data
• boolean data
• date and time data.

VERIFICATION AND VALIDATION

In order to get the best results with your data, you will need to make sure that it is accurate. To do this, you will need to first verify the data and then validate it.

Data verification is the process of checking that the data a user has inputted is correct. This can be largely automated, providing someone has set up the rules on the spreadsheet or database. For example, the age range of high-school students is usually 14 to 18 and the spreadsheet can be set up to only accept an age in that range. This is called a range check. This does not always mean that the data will be 100% correct though. If a student is 15 and the user types in 17, the data is still valid in the range, it is just not correct.

Data verification is mainly used when data is entered into a system manually (that is, a human has entered the data into the database or spreadsheet) and there is a possibility that there will be errors in the data.

Data validation, on the other hand, is the process of making sure that the data that has been transferred from one source to the other matches the original data. For example, if you entered the results of a survey into a spreadsheet, you will check that the results you have match the results you entered.

Data validation also checks to see that the data is complete and matches the requirements of the system in which you entered it. In Access, this is done using data validation rules and input masks.

There are several ways to validate data. These are shown in Table 9.1.

Table 9.1: Data validation techniques

UNIT
 9.3   Software bugs

A software bug is any error, flaw, failure or fault in a computer program or system that causes it to produce an incorrect or unexpected result or to behave in a way that it was not intended to. This can often cause the program to crash (or stop working) or produce an invalid response.

UNIT
 9.4   Hardware failures

Hardware failures are design errors in computer hardware that can cause the hardware to malfunction, fail or be damaged. Some hardware failures can also lead to security flaws in a computer’s system.

REVISION ACTIVITY

QUESTION 1: MULTIPLE CHOICE

1.1Before you analyse data, you must do the following: ______. (1)

A.Spell check it

B.Review it

C.Verify and validate it

D.Organise and simplify it

1.2Information that is incorrectly inputted is referred to as which of the following? (1)

A.Human error

B.Transcription error

C.Transposition error

D.Troubleshooting error

1.3Which of the following is an example of a transposition error? (1)

A.Accidentally deleting an entry

B.Repeating an entry

C.Making a typo

D.Swapping two entries around

1.4Which of the following is NOT a data type? (1)

A.Numbers

B.Strings

C.Dates and times

D.Characters

1.5What does GIGO stand for? (1)

A.Generated Input Generated Output

B.Good Input Garbage Output

C.Good Input Generates Output

D.Garbage In, Garbage Out

QUESTION 2: TRUE OR FALSE

Write True or False next to the question number. Correct the statement if it is FALSE. Change the underlined word(s) to make the statement TRUE. (You may not simply use the word NOT to change the statement.)

a.When we enter data into a computer, the errors that occur are usually computer-based. (1)

b.Transcription errors are most common with text-based data. (1)

c.Human errors negatively impact the validity and accuracy of data. (1)

d.Entering data correctly leads to incorrect results. (1)

e.Binary code is similar to date and time data. (1)

QUESTION 3: MATCHING ITEMS

Choose a term/concept from Column B that matches a description in Column A. Write only the letter next to the question number (e.g. 1J). (5)

QUESTION 4: CATEGORISATION QUESTIONS

4.1Which data validation technique can be used to validate the data in the following scenarios? (7)

4.2Define a software bug. (2)

4.3Define a hardware bug. (2)

4.4Determine if the following errors are caused by software bugs or hardware bugs. (4)

QUESTION 5: SHORT AND MEDIUM QUESTIONS

5.1What is the main difference between data verification and data validation? (2)

5.2How can you automate the data verification process on a spreadsheet? (2)

5.3Describe the two types of data entry errors and give an example of each. (4)

5.4Maryn’s mouse cannot be detected by her computer when she plugs it in. Mention two things she can do to try and solve this hardware bug. (2)

TOTAL: [40]

AT THE END OF THE CHAPTER