Chapter 1 - Lesson 5 (Part 2)

Summary

The video discusses different types of data validation and verification techniques. It explains consistency checks, such as ensuring the gender matches the title on a form, and check digit checks, which use algorithms to verify the accuracy of identification numbers. Verification methods like visual checks and double entry are highlighted as ways to ensure data correctness. Visual checks involve comparing data entered with the original source, while double entry requires inputting data twice to compare for discrepancies. The video also points out limitations of these methods, such as incorrect data being verified if both entries are identical but wrong.

Takeaways

• 🔍 Consistency checks verify that data fields within a record are logically coherent, like ensuring the gender aligns with the title on a form.
• 🧩 An example of a consistency check is when a form prevents selecting 'F' for gender if 'Mr.' is chosen as the title, maintaining logical coherence.
• 📦 Consistency checks can also enforce sequential processes, such as not allowing an item to be marked as dispatched until it is packaged.
• 🔢 Check digit checks use algorithms to validate identification numbers by appending a redundant digit, which helps detect data entry errors.
• 📏 To calculate a check digit, a formula is applied to the primary number, with the result confirming the validity of the number.
• 🧾 Barcodes commonly use check digits, which are calculated using specific algorithms to ensure the accuracy of the product code.
• ✅ Verification ensures that entered data matches the original source, providing an additional layer of accuracy beyond validation.
• 👀 Visual checks are a verification method where users manually compare the data entered with the original source to confirm accuracy.
• 👥 Double-entry verification involves entering data twice and comparing the two entries; if they match, the data is verified.
• ⚠️ Verification methods like double-entry can still allow errors if incorrect data is entered consistently both times.

Q & A

What is a consistency check in data entry?

A consistency check ensures that information entered into a system follows logical rules and relationships between fields. For example, entering 'Mr.' as a title and 'F' for female in the gender field would trigger a consistency check error because these values contradict each other.

Can you give an example of a consistency check involving product dispatching?

Yes, a consistency check in product dispatching would prevent marking an item as 'dispatched' if it hasn’t been marked as 'packaged' first. The system ensures that steps follow a logical order.

What is a check digit and how is it used in data validation?

A check digit is a number or letter added to the end of an identification number to help verify its accuracy. It's generated through a mathematical formula applied to the digits in the identification number and serves as a validation tool.

Can you explain the process of calculating a check digit using a barcode as an example?

For a 13-digit barcode, you add all the digits in the even-numbered positions and multiply the result by 3. Then, add the digits in the odd-numbered positions. Add the two results together and divide by 10. The remainder is subtracted from 10 to get the check digit. If the result is 1, the barcode is valid.

What is the difference between validation and verification in data entry?

Validation checks if the entered data meets certain criteria (e.g., an age field requiring a value ≥ 18). However, it doesn’t ensure the data is sensible. Verification ensures that the data matches the original source and is correct.

What are the two methods of verification in data entry?

The two methods of verification are visual check and double entry. Visual check involves manually comparing entered data with the original source. Double entry involves inputting data twice, and the system checks for discrepancies.

What is the visual check method of verification?

Visual check is when the user manually compares the data entered on a screen with the original source document. If they match, the data passes the verification process.

What are the limitations of visual check as a method of verification?

The limitation of visual check is that it doesn't ensure the original data is correct. If the source document has errors, those errors will be carried into the system, even if they pass verification.

What is double entry in data verification?

Double entry involves entering the same data twice. The system compares both entries, and if they match, the data is verified. If there's a discrepancy, one of the inputs must be incorrect.

What are the potential issues with double entry verification?

If the same incorrect data is entered twice, double entry verification can still pass because both inputs match, even though the data is wrong. For example, if the caps lock is mistakenly left on during both entries, the system will see them as identical.

Outlines

00:00

🧩 Understanding Consistency Checks

This paragraph explains what consistency checks are and provides examples. A consistency check ensures that related data in different fields of a form aligns correctly. For instance, if the title 'Mr.' is selected, the gender cannot be set to 'Female,' as this would create a contradiction. Another example includes not marking an item as 'dispatched' before it has been packaged. These checks help prevent contradictory or illogical data from being entered into a system.

05:01

🔢 Check Digit Explained

This section introduces the concept of a check digit, which is a number added to the end of an identification number to ensure the validity of the data through an algorithm. For instance, a number such as 20392 may generate a check digit of 4, which would be appended to the original number, making it 203924. The check digit is used to verify the integrity of data, such as product codes or identification numbers, by ensuring that they follow a valid structure.

📊 Another Example of Check Digit Validation

This paragraph provides a more detailed example of how check digit validation works, specifically using a product barcode. To validate a 13-digit barcode, a specific calculation process is followed, including adding digits in even and odd positions, multiplying, and performing modulo operations. The check digit ensures that the barcode is valid and any error in this process would result in an invalid product code. The steps involve arithmetic operations that confirm the final check digit is correct.

👁️‍🗨️ What is Verification? Methods Explained

This section distinguishes between verification and validation. Verification is the process of ensuring that data entered matches the original source, while validation checks whether the data meets predefined criteria. Verification can be done through visual checks, where users compare data on the screen with the original source. However, this method has limitations, as errors in the original data will still pass through verification. Verification methods also include double entry, where data is input twice and compared by the system to ensure accuracy.

✍️ Visual Check and Double Entry Verification

This final paragraph elaborates on two methods of verification: visual checking and double entry. Visual checking involves manually comparing data entered into a computer with the original source, but this does not guarantee correctness if the original data is incorrect. Double entry requires entering the data twice and the system checks for any discrepancies. However, if the data is entered incorrectly both times, the error could still pass, highlighting a potential weakness in the system.

Keywords

💡Consistency Check

A consistency check is a validation method used to ensure that data fields within a record do not contradict each other. For example, in the video, if a person enters 'Mr.' as their title but selects 'F' for female as their gender, a consistency check would prevent this mismatch. It ensures that related data fields maintain logical coherence within the form.

💡Check Digit

A check digit is a digit added to an identification number or product code that helps validate the accuracy of the data. In the video, the check digit is described as a redundancy check for things like product codes or barcodes. An algorithm calculates this digit, and if it matches the expected value, the data is considered valid.

💡Validation

Validation refers to the process of checking whether the data entered into a system meets specific criteria or rules. For instance, the video gives an example where a validation rule ensures that a person’s age must be greater than or equal to 18. However, it does not check if the input is sensible, such as entering 140 for an age.

💡Verification

Verification is the process of ensuring that the entered data matches the original source. The video mentions two methods of verification: visual check and double entry. Verification checks the accuracy of data entry, unlike validation, which only ensures the data fits within set rules.

💡Visual Check

A visual check is a verification method where a person manually compares data entered into a system with the original source. For example, in the video, if someone enters an employee’s name into a computer system, they visually check the name on the screen against the name on the original document.

💡Double Entry

Double entry is another verification method where data is entered twice, either by the same person or two different people. The system compares the two inputs. If they match, the data is verified. In the video, an example is given where two people enter the same name, and the system ensures both entries are identical.

💡Algorithm

An algorithm is a step-by-step procedure used to perform calculations or solve problems. In the video, algorithms are used to calculate the check digit for barcodes or product codes. The system performs a series of mathematical steps to validate that a product code is correct.

💡Modulo Operation

The modulo operation refers to finding the remainder when one number is divided by another. In the video, a modulo operation is used in calculating the check digit for barcodes. The video explains how to calculate the remainder after dividing the sum of certain digits by ten to verify a barcode.

💡Redundancy

Redundancy in the context of data refers to additional information that is not necessary for identification but is used for validation. In the video, the check digit is described as a redundant element because it does not serve to identify the product but ensures that the identification number is valid.

💡Contradiction

A contradiction occurs when two pieces of data conflict with each other. The video explains that a consistency check helps prevent contradictions in a form, such as entering 'Mr.' as the title but 'F' for female as the gender. The system would not accept these inconsistent entries.

Highlights

Consistency check example: If you input Mr. as a title and F as gender, a consistency check will prevent this contradiction.

A consistency check ensures that actions like dispatching an item are only allowed after it has been packaged.

A check digit is a number added to the end of an identification number for validation purposes.

Example of check digit: For the number 20392, a calculation results in a check digit of 4, added to the end.

Check digit validation is used for 13-digit barcodes to ensure product code correctness.

To calculate a check digit for barcodes, specific steps like summing even- and odd-numbered digits, multiplying results, and using modulo 10 are involved.

If the check digit calculation does not match, the product code is invalid.

Verification ensures that data entered into a system matches the original source data.

Two verification methods are visual checking and double entry.

A visual check involves comparing data on screen with the original source to confirm its correctness.

Visual checks can still fail if the original source data is incorrect.

Double entry involves inputting data twice, and the system compares the entries for consistency.

If both entries match during double entry, the data is verified.

Even double entry can fail if both users make the same mistake, such as leaving the caps lock key on.

The lesson highlights how validation ensures data meets criteria but doesn't always ensure its accuracy.

Transcripts

what is a consistency check give

examples so consistency check on page

date in one field of data in another

field that already exists within a

record to see where the birth are

consistent with each other so if you

think of a form for example that will

work let's look at the gender in terms

of filling out a form

so when entering the gender of MOF a

consistency check will prevent F from

being entered if the title is m'allister

so in a form you might have to fill in

your title your name your surname so if

you put mr. as your title and you go and

put F for female as your gender that is

conflicted and a contradiction so the

system will prevent you from using F as

your gender in that case so in order for

the system to accept information you

have to say mr. and M for gender when

entering data by dispatching products it

would not be possible to mark an item

has been dispatched until after it has

been packaged so that's also another

example of a consistency check what is a

check digit check give an example so

check digit check is probably one of the

more complicated ones so it involves

some formula being used on the most

common examples like a product key or in

this case what they talking about here's

an identification number so check there

just is a number or letter that is added

to the end of an identification of a

being input it has a form of redundancy

check because the check digit is

redundant and not needed for the

identification number but just used for

validation so we've got some examples

over here let's say you have an original

identification number of 2 0 3 9 2 and

there's gonna be some calculation or

algorithm that is performed on 2 0 3 9 2

so if 2 0 3 9 2 is a accepted

identification number then it's going to

from this algorithm or calculation by

adding or subtracting or dividing or

multiplying these numbers together

it's some way it's gonna get a check

digit of four so there's an example on

the next slide on how this might

specifically work so then the check

digit is forces can be added on to the

original identification number so the

four is just gonna go on the end let's

have a look on the next slide okay so

give another example of a check digit so

this is gonna be a probably little bit

easier than examples on the previous

slide so let's just get all these

bullets up there we go okay so let's say

you're working with some bar code some

product code and the check digit W here

is one okay so hopefully the steps

described here give you a check digit of

one because that is what this image is

showing so the unique product code EPC

check that it is used with 13 digit bar

codes it is the law such as shown on a

bar code the algorithm for cockily in

the check digit is so to get this one at

the end what you got to do is follow

these steps and you should get one if

you don't get a one off the following

these steps it just means that this bar

code or product code is invalid it's not

correct so you can even test this on a

calculator add all the digits in even

numbered positions together multiply the

result in one by three that all the

digits in odd numbered positions

together add results two and three

together divided the result that you got

a number for above by ten so step six

calculate the remainder modular tin of

the result five above so in other words

when you divide the number in four by

ten what is the remainder that you get

is what's modulo ten is referring to and

it subtract six that value from ten and

that should give you one if this product

code is valid so this is an example of a

check digit check what is

verification what are the two methods of

verification the verification is the

process of checking that the data

entered into the computer system matches

the original source visual check in a

double entry our methods of verification

so validation was just making sure that

the data that you typed in made a

specific like criteria so for example

let's say the age 1 you got to make sure

that the age of the person was grading

equal to 18 it's just making sure that

you put in some number which is greater

equal to 18 but the problem with

validation it doesn't actually check

that that information is sensible so for

example someone might type in 140 for

the age but they've made a mistake when

entering it but validation rule for that

box might still accept it because that

age is going to equal to 18 so

verification comes in to make sure that

the data that you enter is actually

correct that it matches the original

source that you are using so visual

check in a double entry all the methods

that we are going to discuss a

verification so what is visual check e

competitor verification can be for the

user to visually check that the data

entered matches the original source this

can be done by reading the date of the

spend on the screen and comparing it

with their original data if the data

matches then it has passed a

verification process if it does not

match then it has failed the

verification process and needs to be

reentered so that's simply like you take

in the page you're entering information

into a computer system so if you type in

an employee's name for example or for

page that you've been given into the

computer once you've typed that

information onto the computer the

ploidies name you just look at the page

you look at the screen and you just make

sure that the information or an

employee's name is the same so as what

is meant by visual checking visual

checking does not ensure that the data

entered is correct if the original data

is wrong then the verification process

might may store pause for example if the

intended date is ABCD but ABC is on the

source document then ABC or the

entered into the computer and verified

but it should have been ABCD in the

first place so their problem with visual

checking is that if the original source

that you are using to enter this

information to the computer system is

wrong then information that is read into

the computer system will be wrong

because that's information that the

person has received to put into the

computer system so last one is what is

double entry so another method of

verification is to input data into the

computer system twice the two items of

data are compared by the computer system

and if they match then they are verified

if there are any differences then one of

the inputs must have been incorrect so

you have two people entering information

maybe for example so let's say if you in

putting the person's first name and st.

John into a computer system after one

person types in John the other person

types and John the computer then

verifies that information by checking

that they're the same and it's all the

same minutes entered but let's say for

example that the information is

different if someone typed John another

person typed Joh and let's say in off

because it's not the same then then that

information is incorrect and the

computer system like put in put out an

error to state that it is still possible

to pass double entry verification and

for the data to be incorrect if the data

is entered incorrectly twice then the

two values may match eg if the caps key

is left on by the by mistake then both

entries would match so that is double

entry okay so that's the end of lesson I

hope I was the right please let me know

if you have any questions