IT Chapter 1: data processing and information

data

raw numbers, letters, symbols, sounds, or images with no meaning

Information

data that has been given meaning

Direct data

data collected for a specific purpose or task and is used for that purpose and that purpose only

Indirect data

data obtained from a third party and used for a different purpose to that for which it was collected

Questionnaires

a set of questions that are easy to distrubute, complete and collect. can be completed on computer or paper - direct data source

Interviews

a formal meeting between two people. gives the interviewee the opportunity to expand on their answer - direct data source

Observation

data collectors watch what happens in a given situation - direct data source

Data logging

using a computer and sensors to collect data - direct data source

Weather data

data that comes from weathering stations and later sold to other companies -indirect data source

Electoral registor

a list of adults entitled to vote in an election, contain personal information such as name, address, age, etc. -indirect data source

Data brokers

businesses collecting data from third parties. usually sold without the indivisuals knowledge - indirect data source

research

from textbooks journals and websites - indirect data source

census

usually carried out by the government to determine the number of people in the country and information collected about them, usually collected in the form of a questionnaire. -Indirect data source

advantage of direct data

we know how reliable it is because we know where it originated

disadvantage of indirect data

we may not know where the data originated and it could be that the source is only a small section of that group rather than a cross section of the whole group (sample biasing)

disadvantage of direct data

because of cash and time restraints, the sample or group size may be small whereas [blank] data sources tend to provide larger sets of data

advantage of indirect data

the person collecting the data may not be able to gain physical access to particular groups of people (usually due to geographical reasons) whereas [blank] data sources allows data from such groups

advantage of direct data

the person collecting the data can use methods to gather specific data even if the data is obscure

disadvantage of indirect data

the data might be so obscure it has never been collected before

disadvantage of direct data

it may not be possible to collect original data due to the time of the year while in [blank] data, historical weather data is available irrespective of time of the year

advantage of direct data

the gatherer only needs to collect as much or as little data as neccessary

disadvantage of indirect data

irrelevent data may need to be removed

disadvantage of direct data

by the time all the required data has been collected it may possibly be out of date so an indirect data source could have been used

advantage of direct data

may be opportunities to sell the data later on, reducing the expenses of collection

disadvantage of direct data

the collection of data may be more expensive than using an indirect data source as many people would have to be payed for the collection

accuracy

factors that affect quality of information 1

relevance

factors that affect quality of information 2

Age

factors that affect quality of information 3

level of detail

factors that affect quality of information 4

completeness of information

factors that affect quality of information 5

risk of not encrypting your data

identity theft, cyber fraud, ransoming. if related to company secrets could be sold to rival companies

process of encryption

plaintext → encryption algorithm + encryption key → ciphertext → decryption algorithm + decryption key →plaintext

symmetric encryption

involves the sending & recieving computer having the same key to encrypt and decrypt data. it is very fast but not as secure

assymetric encryption

involves 2 keys, 1 public which is distributed among many users or computers to encrypt the data. while a private key is only available to recieving computers, and used to decrypt the data

secure socket layer/transport layer security

• enables encryption

• enables authentication

• makes sure data has not been corrupted or altered

• ensures websites meet the payment card industry data security standard (PCI DSS)

• improves customer trust

internet protocol security (IPsec)

an extension to the IP layer to provie authentication, integrity, and confidentiality of data.

the use of SSL/TLS in client server communication

used for applications to be securely exchanged over a client server network, such as web browsing and file transfers

the use of IPsec in client server communication

used to protect confidential data transmitted across a network within businesses, such as financial transactions or medical records. mostly used in VPN

data protection

use of encryption 1

system encryption

use of encryption 2

hard disk encryption

use of encryption 3

email encryption

use of encryption 4

encryption in HTTPS websites

use of encryption 5

validation

ensures that data is reasonable and sensible but not necessarily correct. always done by a computer.

presence check

make sure data has been entered in certain fields

range check

makes sure numeric data falls betweens a minimum and maximum value

type check

ensures data is a particular data type

length check

ensures data is a certain number of characters. not used on numeric fields. can be set to a range

format check

makes sure the data follows a certain pattern

check digit

an extra calculated digit is added to the data and when this check recalculates it. if the digit is the same the data goes through

lookup check

compares the data that has been entered to a limited number of valid enteries

consistency check

checks the data across fields is consistent (e.g someone born in 2010 can not have their grade level be grade 12)

limit check

like range check but with only one maximum or minimum boundary

verification

ensures data has either been entered accurately by a human or that is has been transferred accurately from one storage medium to another.

visual checking

the person entering the data visually compares data they have entered with that on the source document. this can also be done with 2 people, 1 to type and 1 to double check

this is time consuming and costly as a result

double data entry

involves entering the data twice, the first version is stored and the second entry is compared by a computer and the person is alerted to any differences

alternatively, another person could enter the data the second time and is alerted of any differences as they are typing

Parity check

• data is being transmitted from 1 device to another,

• the sending device counts the number of 1s in each byte

• if the number of bytes is even, it sets the parity bit to 0 and adds this to the end of the byte

• if it is odd, it sets the parity bit to 1 and adds it on

• the other device recieves and checks if the number of 1s is even, if not, the data has been altered

checksum

• used for WHOLE files of data. not bytes

• can be any calculation ( such as sum of the number of bytes in the file)

• the problem with it is that it can not detect a change in position of bytes

• the digit is added to the end of the file and recalculated after the transition to make sure nothing has changed

hash total

• a calculation performed using the data before it is sent, then recalculated, like checksum

• however the digit is usually found by adding up all the numbers in a specific field or fields in a file usually with non-numeric values

control total

calculates in the same exact way as hash total except there is no need to convert alphanumeric fields to numeric because it is only carried out on numeric fields

advantage of validation & verification

make systems more accurate, ensuring the data is copied accurately and ensuring that the data is sensible

disadvantage of validation and verification

both tend to slow down the processing of data with neither method checking if data is correct

batch processing

• effective for processing large amounts of data

• entered and processed altogether in 1 batch and requires little to no human interaction

• used in payrolls and billing systems

master file

file that contains all the important data that does not change often, such as names, workers number, hourly rate

transaction file

file that contains data that changes each week such as hours worked