Methods of verification and validation of data

GOOD DAY, students. This is lesson 10 in our series of lessons. In this week’s lesson, we will look at the key concepts of methods of validation and methods of verification for information stored.

Before we examine the different methods of verification and validation of data, we need to examine some errors that may occur during the entry of data into a computer system or the sending of data. TRANSMISSION ERRORS

This is when data received by a computer or system is not the same as what was sent by another computer. It could be as a result of an electrical fault or faulty cabling, as well as the computer used to send the data. EXAMPLE yyyyyoooo is transferred as x&*`^$yyoo TYPOGRAPHICAL ERRORS

These are errors made typically by humans when we are typing data. This can also be said to be an accidental error (errors that are not made on purpose). For example, typing in a wrong date of birth. EXAMPLE

I forgot my password to my nstagram account.

TRANSPOSITION ERRORS

These are errors made when numbers or characters are placed in the wrong order. An example of this could be when we are typing a date of birth for someone who was born on the 12th of September 1998 and ww type 09/12/98 instead of the 12/09/98. EXAMPLE

I swa Avengers: Engame on Friday. It was epic!

Some errors can also be considered to be deliberate, where they are made by humans intentionally for personal gain or just to create disruption. For example, someone may falsify a document to gain acceptance in an institution or for a scholarship.

There are two ways of preventing errors made by humans and they are data verification and data validation. Data verification is a process carried out by humans, whereas data validation is an automatic process carried out by software. DATA VERIFICATION

Data verification is the process of checking for errors that might have been entered in the computer from a source document or when data is copied from one medium

or device to another. Two methods of data verification are double entry and proof reading/visual checks.

The double-entry method is the process of entering data more than once using a program that checks each second entry against the first. If the data entered is not the same, it will not get processed and the system will allow for the re-entry of data to ensure the data entered is accurate. An example of this process would be when you are required to enter your password twice when setting up your email to confirm your password. Proofreading, on the other hand, checks the data entered against the data on the original source document. This method can be time-consuming, as it requires the user to read the information from the source document and check it against what was entered in the system.

Visual checks utilise on-screen prompts. When a set of data is entered, it is redisplayed on the screen. The user is prompted to read it and give a confirmation that the data entered is correct. If the data is incorrect, the data is re-entered. DATA VALIDATION

Data validation employs several ways of checking for the accuracy, consistency and completeness of data. Let us examine the most popular methods that can be used to validate data. RANGE CHECKS

Range check ensures that the data entered is within a particular range. Examples of such a check would be data pertaining to the number corresponding to the months of a year and not exceeding the number of hours in a day. REASONABLENESS CHECKS

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realistic. For example, a student enrolled in first form with a particular date of birth, his or her age, when calculated by the computer system, should correspond (say age 11). Thus, a child who is 17 years old cannot be linked to a date of birth younger.

DATA-TYPE CHECKS

Data-type checks, also called character checks, ensure that the right type of data has been entered. They ensure that if you intend to enter numbers, only numbers are allowed to be entered; and if only characters or symbols are intended to be entered, then only that type of data is allowed. For example, if you are storing someone’s name, only letters would be entered; values would not be allowed.

CONSISTENCY CHECKS

Consistency/inconsistency checks compare data you have entered against other data you have entered. If you enter a person’s year of birth and age in separate fields, a consistency check will ensure that the two fields correspond with each other. Thus, if the age of an individual is not in line with his/her date of birth, then this would be considered to be inconsistent.

PRESENCE CHECKS

This check ensures that required data is always present. For example, in a database, information is stored on a set of employees and each employee must have an ID number. A presence check will ensure that the ID field is not left blank. On the other hand, there are cases where some fields in a database may be optional; for example, not everybody may have a house number, but they have a cell phone. So, the field which stores a customer house number may be left blank.

FORMAT CHECK

A format check is a validation check which ensures that entered data is in a particular format. The format that data must be in is specified using an input mask. The input mask is made up of special characters which indicate what characters may be typed where.

LENGTH CHECK

Most databases will automatically perform length checks on any entered data. The length check is a validation check which ensures that the data entered is no longer than a specified maximum number of characters.

We have come to the end of this lesson. See you next week, when we will look at file access methods. Remember, if you fail to prepare, you prepare to fail.