Cambridge AS level- IT Chapter 1

Data

Raw numbers, letters, symbols, sounds or images without meaning

Information

Data with context and meaning

Direct Data Source

Data That is collected for the purpose for which it will be used

Indirect Data Source

data that was collected for a different purpose (secondary source)

3 Pros of a Direct Data Source

~ The data will be relevant because what is needed has been collected

~ The original sources is known and can be trusted

~The data is likely to be up to date

~Bias can be eliminated

~The data is goin to be in the format that is required

3 Cons of a Direct Data Source

~ The data takes a long time to gather

~A large sample of statical data can be difficult to use for one-off purposes

~ Uses many resources to collect the data

Resources == Money

How to check the quality of the information?

through

~Accuracy

~Relevance

~Age

~Level of detail

~Completeness

What does it mean to have accurate data?

When information is clear and does not have mistakes like

turning $90.30 to 903.00 with the decimal point in the wrong place

Encryption

Process of converting readable data into unreadable characters to prevent unauthorized access.

Symmetric Encryption

An encryption method whereby the same key is used to encode and to decode the message

Asymmetric Encryption

two keys are used; one key encodes the message, and the other key decodes the message. The public key is used to encrypt the message, while the private key is used to decrypt the message

SSL

(secure socket layer)-

a security method used for securing a website

TSL

(transport layer security)

has taken over SSL

makes the secure communication faster

HTTPS

Hypertext Transfer Protocol Secure.

encryption standard used for secure web pages

Validation

the process of checking data matches acceptable rules

What does a range check?

It ensures that data is within a defined range

~ > less than

~ = less than or equal to

~ <= greater than or equal to

What is a type check?

Ensure the data must be of a defined data type

Ex: If a date of birth is entered, it must be numerical and in date form

what is length check?

ensures data is of a defined length or within a range of lengths

Ex: a password must be at least six character long

what is lookup check?

tests to see of data exists in a list

Ex:

when a user is asked for their gender they respond with either "Male", "Female" or "Nonbinary"

what is a consistency check?

compares data in one field to data in another field, that already exist in the record, to check whether they are consistent with each other

What is a check digit?

A check digit is an additional digit at the end of a string of other numbers designed to check for mistakes in input or transmission

Verification

ensuring data entered into the system matches the original source

what is visual checking?

a method of verification in which the user visually checks that the data entered matches the original source.

what is double data entry?

Data is input into the system twice and checked for consistency by comparing.

What is a Hash Total Check?

The hash total of items processed is compared to a predetermined number. This number is not of any use.

what is control total?

The amounts—usually representing the number of items, their total or other key information—used to help verify that received files are unchanged from the original transmitted files. The number is useful

What is a checksum?

A method of error checking that determines if the contents of an arriving data unit match the contents of the data unit sent by the source.

batch processing

Accumulating transaction records into groups or batches for processing at a regular interval such as daily or weekly. The records are usually sorted into some sequence (such as numerically or alphabetically) before processing.

master file

A permanent file of records that stores cumulative data about an organization. As transactions take place, individual records within a master file are updated to keep them current.

transaction file

data that is used to update a master file

online processing

Also known as interactive processing, data is input by the user, and feedback is given in the form of outputs

How is online processing done?

Once the data for the transaction is collected it is processed and the next transaction can occur.

real-time processing

data is processed as soon as it has been input and outputs are generated immediately