ICT AS - INFO2 - Chapter 10 - Data and Information

Revision cards for Chapter 10 - Data and Information.

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Introduction

Data is collected in many different ways on a regular basis about everyone.

We must understand what happens to this data when it is processed to produce information that individuals and organisations use for various purposes.

Input ----> Process ----> Output

In some systems, the output is fed back into the system and modifies it until the correct output is produced.

Good quality information can be used by humans to aid the decision making process.

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What is Data? Types of Data

Data is raw facts/figures/set of values

Three forms of data:

  • Text - A/Z, lowercase, uppercase
  • Image - Vector map, Bitmap
  • Number - 0 to 9

Bits and Bytes:

  • A single unit of binary is called a "bit" (Binary digit).
  • Computer memory is measured in "bytes".
  • One byte is 8 bits.
  • One byte holds one character. The 8 bits determine what character it is.
  • A kilobyte is measured as 1024 bytes. Over 1000x bigger than a byte.
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Coding and Encoding

When data is collected, it may need to be coded

Coding data is necessary in order to be processed efficiently.

An example of this is when you are asking someone the quality of a restaurant. People will give various types of answers.

Asking on a scale of 1-5 means only a single digit would need to be entered. 

This makes comparisions with other restaurants easier as all that needs to be compared is the single digits given by the people.

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Coding and Encoding

Encoding is used to convert data into a machine-readable form

Computers can only understand binary which consists of 0s and 1s. It is difficult for humans to understand.

Therefore the data must be encoded from our language into binary in order for the computer to use it.

One method used for encoding is ASCII which represents each letter as a binary number.

Some data is coded before storage and changes the original data into a shortened version by assigning a code.

This is done to keep it short, save storage space and speed up data entry. 

Examples: M or F for Male and Female. Y or N for Yes and No.

Coding can be inaccurate and codes can be difficult to remember.

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Bar Codes

Bar codes are very versatile. They can be read from a variety of angles and even when upside down.

One key feature is the automatic check for any data errors through the use of validation.

Bar codes have stood the test of time for coding and automatic data capture. RFID seems to be a more popular choice now.

Bar codes are used in student cards, products in warehouses, supermarkets. 

ISBN coding system is used on printed books. They all have a unique number which is a composite code.

ISBN number is printed on the back of books in a bar code format so it aids stock control.

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Processing Data

Processing is the work the computer does to convert the data into information. This may involve calculations, logistical operations or even altering a sound wave.

Information is data that has been processed into something meaningful.

Examples:

  • The data from a barcode is processed to produce a reciept with the item names and prices included.
  • Raw examination marks are entered as data. Processing involves standardising the scores. The output would be the final grades presented in a graphical form (a graph).
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Quality of Information

Information is a commodity. It can be bought and sold. Therefore, it potentially has value.

Information increases in value if it is:

  • Accurate - If information on a sales report is inaccurate, any monetary decisions made will be inaccurate and can cause damage to a business.
  • Up to date - Share prices need to be up to date.
  • Complete - If a house is being insured and the information does not contain the actual cost of the house, the information is incomplete.
  • From a reliable source - Trusted sources (BBC, newspapers) are the best sources for information. Wikipedia can be edited by anyone, possibly leading to false information.
  • Relevant - If the information has no use to a particular person, it loses its value.
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Comments

Daniel Gero

Text - A/Z, lowercase, uppercase

If a byte holds one character and it has 8 bits, and a bit can either be true or false, then there are 2 ^ 8 possible characters for a byte. (that is 256).

So in fact a byte has the possibility to hold A-Z, 0-9, latin characters, the Chinese alphabet,  Wingdings-like symbols, and more. 'Text' certainly does not mean only A-Z.

"Image - Vector map, Bitmap"

In real life (outside of Microsoft), there is no 'image' data type. Image is just the way bytes are interpreted to be displayed. When you store an image in the database, you just store the bytes of it; a list of bytes. Same for any file or any data you put into the record. And it is no different if you store a vector or a bitmap because it is just the bytes of that data.

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