What is data?
Chapter 1
Introduction
• This presentation covers the following:
– What is data?
– What is information?
– Representing data
– What is knowledge?
– Data Types
What is data?
• Looking at these pieces of data:
–
–
–
–
11071984
106.16
CV12BT
94500000
• What do the pieces of data represent?
What is data?
• Looking at these pieces of data:
–
–
–
–
11071984
106.16
CV12BT
94500000
– Birthday? Historic Event? Member ID?
– Average score? Distance to something?
– Post Code? Licence plate?
– Diameter of a planet? Seconds I have lived?
• What do the pieces of data represent?
What is data?
Data
The raw facts and figures
Structure
How the data is presented. Are the numbers actually numbers or
should they be read as text?
Context
An environment where our prior knowledge and understanding
can make sense of data.
Meaning
Data in the correct structure and placed within context.
Knowledge
The application of information to a solution.
Information = Data + Meaning
Information = Data + [Structure] + [Context] + Meaning
Data representation
• Data can be presented in different ways.
• Presenting data in different ways has its
advantages and disadvantages.
• Thinking about the way the data is to be used
and who will be using it will help you chose
the best way to present the data.
Data representation
• Text
– Advantages:
• Clear to understand
• Detailed
– Disadvantages:
• Need to be able to read the text and understand it
(different languages)
• Can it be read by all ages or is it too confusing for
children?
• Lots of text takes time to read and may not be suitable.
Data representation
• Graphics
– Advantages:
• Good designs can be understood by people who speak
different languages.
• You can match images to what you can actually see.
– Disadvantages:
• Some graphics you need to learn in order to understand
them (road signs, scientific symbols)
• Some graphics/symbols mean different things in
different countries.
Data representation
• Sound
– Advantages:
• Great for visually impaired people
• You don’t need to have ‘line of sight’
• No fixed location required.
– Disadvantages:
• Large areas will end up distorting the sound.
• Usually language based.
• May need to learn what different sounds mean (fire
alarm, school bell etc)
• Need to be able to hear.
Data representation
• Moving images
– Advantages:
• No language required
• Lots of information can be conveyed
• Can be used to show the meaning of the text
– Disadvantages:
• If you miss the beginning you might not understand the
meaning.
• May be a problem if sound is also required.
Data representation
• Graphics
– Advantages:
• Good designs can be understood by people who speak
different languages.
• You can match images to what you can actually see.
– Disadvantages:
• Some graphics you need to learn in order to understand
them (road signs, scientific symbols)
• Some graphics/symbols mean different things in
different countries.
Data representation
• LED
– Advantages:
• Can be simple to understand if context is clear.
• Can be used in noisy places.
• Can allow data to be kept secure.
– Disadvantages:
• Need to be able to see lights.
• May need to know what combinations of lights mean.
Take note:
• Give three situations where the use of sound
to convey information would be appropriate.
• Give three situations where the use of text to
convey information would be appropriate.
• Why are road signs symbols and not text?
Data  Information:
Data
Structure
Context
Meaning
12102005
12/10/2008
UK DATE
Date of a hotel booking
31 32 34 32 31
Numbers
Celsius
Temperatures for the last 5
days in Venice
SKBL10
First 2 letters: Type of garment
Second 2 letters: Colour
Last 2 numbers: Size
Shop stock code
A black shirt, size 10
1
Selected from a scale of 1-4
How enjoyable
was the film? 1Good, 4 – Bad
The film was good
Take note:
• Fill in the following table using the contexts
which are given:
Data
Fish Shop
Holiday Website
TV programme
listing magazine
...you choose one...
Structure
Context
Meaning
Take note:
• Answer the following questions:
– Give a definition of information.
– Within the definition of information, what is
meant by structure?
– Within the definition of information, what is
meant by context?
– Within the definition of information, what is
meant by meaning?
– Within the context of a car sales garage, show
how data can become information.
What is knowledge?
• Think of knowledge as the application of
information.
• For example,
– Data: 62, 57
– Information: Driver Standings for Hamilton and
Raikkonen, respectively, after Hungarian Grand
Prix 2008
– Knowledge: Hamilton is leading the
championship.
What is knowledge?
• As we receive more information our
knowledge may change in accordance with
what we have learnt.
• For example,
– Data: 62, 62
– Information: Driver Standings for Hamilton and
Raikkonen, respectively, after the following race.
– Knowledge: Hamilton and Raikkonen are now tied
for the championship.
Data Types
• It is important to use the correct data types when storing
data.
• Different data types are selected depending on how you
want to use the data and what the represent.
• There are five different data types you need to be familiar
with:
–
–
–
–
–
Boolean
Real
Integer
Text/String
Date/Time
Boolean
• Essentially, the simplest of all data types.
• It can only contain one of two possible values:
–
–
–
–
True or False,
Yes or No,
Male or Female
Etc
• Consider the following examples:
– Is the motorway open yet?
– Is Hamilton winning the race?
– Are you dead?
Real
• This data type contains numbers with decimal
values.
• It holds values where precision is important.
• Consider the following examples:
– Price of bread - £1.20
– Car length – 4.2 metres
Integer
• Used to store WHOLE numbers only.
• It does not allow decimal places to be stored.
• Consider the following examples:
– Age in years – 24
– Code response – 1 to 4
Text/String
• This is any alphanumeric number.
• It can contain numbers, symbols, text or a combination of all of them.
• Consider the following examples:
–
–
–
–
–
12345
Mickey Mouse
123GD56
101 ICT Road

• Use Text/String if you want to store a number that is not going to be used
for any calculation.
• A common mistake is to store telephone numbers as an integer, but
because numbers start with a zero it is often removed when saved.
Date/Time
• Depending on the format used, it can save numbers or
numbers and text.
• Consider the following examples:
– 12:45:45
– 1995
– 7th September 2007
• A computer will work out dates using numbers, but we
format dates so we can understand them better.
Take note:
• Within the context, give an example of how
each data type could be used:
Estate Agency
Boolean
Real
Integer
String
Date/Time
Removal Company
School
Choosing the correct data type
• Its important to select the correct data type
because certain processes can only be carried out
on certain data types.
– Combining text values to create a new string can only
be done using the text data type (this is known as
concatenation).
– Storing a range of numbers, e.g. 1-4, can not be done
by Boolean.
– Multiplying numbers can not be done using a text
data type.
Take note:
• Using an example, describe the Boolean data
type.
• Give three examples where the use of an
integer data type would be more appropriate
than a real data type.
• Give two reasons why a telephone number is
stored as a text data type.
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