Data and Information

Syllabus for 2.2

Lesson Objectives All students will know the difference between data and information Most students will be able to explain why there is a need to code data Some students will be able to explain why data is encoded with examples

What is the difference between data and information? 5 minutes What is the difference between data and information? Students to pair and share their home learning from last week

Product information after scanning in the barcode Data Is raw facts and figures which have not been processed. Product information after scanning in the barcode What product information is shown on the screen after a barcode has been scanned? Information Is data processed by the computer into something with meaning.

There are FIVE forms of data, how many can you think of… 2 minutes There are FIVE forms of data, how many can you think of… sound text numbers DATA Still images Moving images

Automatic measurements or readings – CAN YOU THINK OF ANY EXAMPLES OF THIS? Results from a questionnaire From a transaction e.g. an order How do we get data? MIS – management information system, takes data and uses this to provide info that people can use to make a decision From the output of another system e.g. MIS From a survey

Data capture… Collection of data to enter into a computer Can be entered in a variety of ways, depending on the source… Keyboard Speech recognition (using a microphone) Webcam Touch screen Selection from list using a mouse Sensors Bar code reader Transfer of pre-captured data from an external device (e.g. a digital camera)

Quality of the Data Source 1 GIGO (Garbage In Garbage Out) If data input is poor the resulting information output will be poor i.e. corrupt, inaccurate etc. Can you think of any “real life” examples? Garbage In Garbage Out

Examples of GIGO Examples of GIGO can include: Unreliable questionnaires/surveys e.g. inappropriate samples, badly worded questions etc. Incorrectly calibrated instruments e.g. an incorrectly calibrated balance will give incorrect measures of mass Human error e.g. transcription errors when entering data Incomplete data sets e.g. failing to account for “shrinkage” when measuring supermarket stock

Shortening data and assigning code – learn this definition for coding! Coding data Title Forename Middle Name Surname DOB Sex Year group Mister James Dean Arthur 22nd May 1994 Male Year 12 Becomes… Title Forename Middle Name Surname DOB Sex Year group Mr James D. Arthur 22/05/94 M 12 Shortening data and assigning code – learn this definition for coding!

Why bother to code data? Easy to remember the data Short – so quicker to enter the data and…. Less chance of making mistakes More data can be seen on the screen – less scrolling Takes up less storage space / compress data Easier to check data being input is correct via validation/verification checks to ensure data is consistent and correct. Only applicable to limited ranges of data – why do you think this is? Banks use 60-40-90 sort codes to identify branches Airports – LHR London Heathrow Airport Can you think of any more??

Drawbacks to coding data Precision of data can be lost (coarsened) In the example all shades of blue are coded as “blue” The user needs to know the codes used How many of these top level domains do you know? au, ch, de, ie, pk, fr, il, lk, es Data in Pink Blue Black Blue Stored data

Coding value judgements Coding value judgements can be a particular problem as they are subject to personal opinion What do you think of this presentation? Good? Average? Poor? One person’s good may be another person’s poor!!! Value judgements are very difficult to encode without some coarsening (loss of detail)

Secret Language… 100 1000 , 100 1001

Write a one word message to your neighbour! Secret Language… Students to write and swap their messages Write a one word message to your neighbour!

What is encoding and why does it exist? Encoding is converting data into machine readable form for example binary code. Exam tips Ask you to compare coding & encoding using an example (usually 4 marks) Just an encoding question – so explain what it means and give example (2 marks) Just a coding question – these ones can be made up of 2,3, 4 mark questions. For example , why do we code (3 marks), example of coding? (1 mark), definition of coding (2 marks)

Encoding image files… Meaning an image is represented in a certain way when it is stored. The way in which an image is encoded depends on how the image was produced. For example by digital camera / scanner / paint or drawing software etc. Types of encoding used for an image: Vector / Bitmap – what is the difference between these? GIF – what is this ext normally used for? JPEG – the most popular format for sharing images online TIFF WMF

Encoding sound files… Sounds are not digital, so to save them on a computer requires data to be encoded. As sound files are quite large compression is used to reduce their file size during encoding. Some popular sound file formats: WAV – used with Windows, files are not highly compressed MIDI – (Musical Instrument Digital Interface) used mainly to communicate between electronic keyboards, synthesisers and computers. These files are compressed to quite a small size MP3 – uses compression to reduce the file size considerably, which is why is it the most popular format for listening to music on portable devices SHOCKWAVE AUDIO – used for very high quality sound with a very small file size.