Topic 2 Data and Information Key The Key concepts for this topic are: Data Date is processed to produce information Information 2.1 What is Data? Data Data can be defined as a set of recorded facts, numbers or events that have no meaning. It can be recorded in education in many ways, such as the results of a Science experiment or a healthy eating survey for Food & Nutrition. In this case the set of data values recorded could be 1, 2, 3, 4, 5, 6, 7, 8; which without a context is simply a list of meaningless numbers. Most textbook examples of data are given as a series of alphanumeric characters (includes the full range of alphabetic and numeric character set); but other forms of data could consist of: images, video and sound. Types of Data Computers are logical devices that manipulate data using binary arithmetic, which briefly means only 2 numbers (0 and 1) are used. Data is stored in bytes which are made up of a series of 8 bits; for example, a byte could be 10011010. So irrespective of the type of data being input into the system it will consist of a series of bytes. Although computer data is based on binary numbers various types of data can be used depending on the way the digital data is interpreted, including the most commonly used: Text / Alphanumeric data types are used where data is text, numbers or a mixture of both. Note that a telephone number needs to be in text format as it usually begins with a zero for the dialling code whereas if the telephone number was in numeric format the leading zero would be deleted. Numeric format data is used where numbers exist that may be part of a calculation. There are various ways the numeric field can be further defined such as INTEGER (example 1245) and REAL OR FLOATING POINT NUMBER (example 25.8). Currency is numeric data that would be based on a floating point number (example 123.45) stored in a special format to main fixed decimal places. Boolean or Logical data is byte sized and is used where only two states for the data are possible, such as True / False, Yes / No, etc. This data is useful in programming or in running database queries where logical conditional statements are used for instance: IF (full_time_student = True) THEN pay_student_grant; AQA AS INFO 2 Course Companion Page 7 of 105 ZigZag Education 2008
Images are commonly stored on computers as either bitmaps or vector graphics as detailed below: Bitmap Graphics can be obtained by creating an image in a drawing package, scanning a picture or uploading a photograph from a digital camera or web cam. In this case the image is composed of a series of individual coloured pixels. There are several bitmap file types including BMP (large file size), JPEG (compressed bitmaps) and GIF (compressed low resolution images suitable for web publication). Vector Graphics are normally produced by a specialised drawing package like computer aided design (CAD). It is where the drawing is constructed from geometrical shapes such as points, lines, curves and polygon(s), which are all based upon mathematical equations, to represent an image. Each object is stored in the image, so a line may have the following characteristics, length, and thickness, the position in x-axis and y-axis and finally the colour. So the whole image is made up of a series of vectors that dictate the position of each shape in the drawing. File Size Note that image files are much larger than text files; the smallest image for a web page thumbnail picture is typically about 25 kilobytes or more. High quality photographic images are much larger than web based images and a typical A4 sized photograph will be about 4.5 megabytes or more. By way of contrasts, text files are much smaller at they are made up of text characters where each character is stored in one byte. Audio data is made up of sound waves (analogue inputs) that have to be converted to digital inputs before any processing can be carried out with them. This is achieved by converting taking a sample of the sound wave and using an analogue-to-digital converter (ADC) to gain a digital sound signal. Sound files in windows are WAV files and they can be quite large. Recently there have been developments to compress these files into MP3 format, which has become the standard for downloading and playing music on portable devices. Video images are made up of a series of images that can include a soundtrack. The common standard used is the compressed MPEG / MPEG-2 file formats. Flash movies can be produced using Macromedia Flash software and are played on a free downloadable flash player; this software is mainly used for producing animations which are stored in SWF file format and have small file sizes. Source of Data Data can be collected from a variety of sources, either directly or indirectly. Direct data is where the data collected is for a specific purpose, such as collecting the customer details, credit card details and the products they have bought in an online shopping transaction. It is obvious that all the data collected in this case is necessary for the online shop to complete the transaction and dispatch the goods to the correct address. When data collected by a company for one purpose is manipulated for a completely different purpose, this is said to be indirect data. Using the online shop as an example, directly collected data on previous purchases could be used to generate an individual customer profile; emails could then be sent promoting goods that are likely to be of interest to the customer. A similar technique is used by the supermarket chain Tesco, where they create a customer profile linked to purchases detected using their Loyalty card. AQA AS INFO 2 Course Companion Page 8 of 105 ZigZag Education 2008
Coding Data In some cases there is a need to code data on collection to enable easier data input. This technique is often used by the operator to shorten the inputs on a paper-based form prior to data entry. Typical codes in this situation could be: Y for Yes and N for No M for Male and F for Female GB for Great Britain DD/MM/YYYY for a date to ensure a consistent input. Coding data has many advantages: It reduces the amount of data storage space required, especially in a large database. It can speed up the process of typing the information in, as there are less keys to press. It makes it easier to validate (check) data as the words on screen are shorter or abbreviations. Coded data takes up less space when it is displayed on screen or a printout. Encoding Data It is necessary to encode data that is input into an ICT system so it is in a form that can be understood by the machine. As already discussed computers only understand binary so in the simple case where we press a key on the keyboard the signal received by the computer has to be converted into a string of binary digits; for keyboard entry only 8 bits or one byte is needed to represent a character; for example, the number 9 is represented by 00111001, which is equivalent to the decimal number 57. The standard encoding used is known as ASCII and in the following table are shown some typical codes for various keys on the keyboard. Decimal Binary Code Keyboard Character 48 00110000 0 49 00110001 1 50 00110010 2 51 00110011 3 52 00110100 4 53 00110101 5 54 00110110 6 55 00110111 7 56 00111000 8 57 00111001 9 58 00111010 : 59 00111011 ; 60 00111100 < 61 00111101 = Images are encoded in much the same way except they use much more storage space. AQA AS INFO 2 Course Companion Page 9 of 105 ZigZag Education 2008
A high resolution photographic image of a building in Barcelona is shown below: When saved as a digital photograph it will be encoded into a series of colours for each pixel; without compression this would make a large image. Compression uses a technique to write formulas to map areas of the image which are the same colour. To express this simply, many parts of the sky in the example are the same colour and so could be saved as a series of large coloured rectangles, which would use less memory than storing each individual pixel. The code for the photographic image of a building in Barcelona is displayed using notepad text editor; this demonstrates that the encoded data is in a machine code and is unable to be understood by a person. The characters displayed are not in binary but a longer machine understandable code for this JPEG image file. The code will change for this image if the file format is changed or it is compressed. Note that image compression is the application of data compression on digital images, whereby redundancy is reduced in the image data so it can be stored in an efficient form. AQA AS INFO 2 Course Companion Page 10 of 105 ZigZag Education 2008
2.2 Data Processing Processing is required to enable information to be produced from data; there are a variety of data processing techniques employed including: Calculations where, for example, the input data is a gas meter reading which is converted into a volume of gas and multiplied by the cost to produce the information required which, in this case, is a final bill. Image Manipulation where the raw data, which is an input image, is processed, for example, by cropping, changing contrast and brightness. The resultant image can be further processed by saving it in a compressed format for website display purposes. Logical Processing where data in a database can be queried using logical operations to produce the information required. A typical example could be querying a database to gain a list of all the people over 18 years old by generating a logical operation on their date of birth. Audio / Visual (AV) Processing in this case AV editing software can be used to adjust sound by, for example, increasing the base and to adjust video by inserting or deleting images (or frames) into the video footage. 2.3 Information Information is obtained when data has been processed to give it context and meaning to the user. Raw Data Processed to give Meaning Information There are many examples where data that has no meaning can easily be processed and turned into information; the following example illustrates the point: Supermarket EPOS Transactions Example 1. At the electronic point of sale the till operator scans each purchase into the system using a bar code device; the bar codes inputted are actually meaningless to a human. 2. The system processes the total transaction and bar code data is used to gain access to product description, name of manufacturer, size of product, cost of product, number of each item purchased, etc. 3. The system then calculates a total for the transaction and prints a receipt with all of this information displayed on it. So the bar code data has been processed to print out information on the till receipt. AQA AS INFO 2 Course Companion Page 11 of 105 ZigZag Education 2008
2.4 Quality of Information Nowadays information is sold on the open market in the same way as any other commodity. Information is also collected by organisations from their own transactions for use in marketing their products and in general decision-making. Clearly the quality of the information will have a direct bearing on the success of any marketing and in the value of any decisions made. The main factors that affect the quality of information are described below: Accurate information can be used for either marketing or decision-making, but in each case it needs to be accurate. A mail merge marketing letter with inaccurate post codes will not reach the intended audience and increase company sales. Relevant information should be relevant and concise; if the user has more information than they actually need they are wasting storage space and may also get confused by considering additional irrelevant facts in their decision-making. If a supermarket is planning to build a new store they would be interested in facts like the size of the local population, where rival supermarkets are located in the area and the availability of suitable sites. The number and location of nearby bars and restaurants is irrelevant in their decision-making and may confuse them. Up to date information needs to be accurate and up to date when it is presented. The decision to restock a DIY store would be unsuccessful if based on stock levels that are three months out of date. Also a customer database that had not been updated for ten years would have many errors in it as people would have moved house, so any mail shot campaign would most likely be ineffective. Complete information needs to have all the essential details needed for a task. A mail shot letter sent as part of a marketing campaign is not likely to yield success if the name of the person at the address is unknown; mailing letters to The Occupier are normally consigned to the dustbin without being opened. In a similar manner calculating the combined sales figures for a well known supermarket in the West Country would be of little use in decision-making if the details for the county of Devon were missing. Understandable it is critical that any information received in a report is understandable by the person who is receiving the report. A company may be considering entering into ecommerce and may commission a website designer to investigate their options and send them a written report based on their findings. The organisation will struggle to make a good decision if the report they receive has lots of complicated technical terms that they don t understand. The report should be written in a style that reflects the capability of the user and if necessary should be actually presented by the author. Timely it is important that information is presented at the time when it is most needed. If decisions have to be made all the information should be on hand to aid the decision-making process. An example of the timeliness of information could be when a company is planning to relocate its offices and warehouse to a new area of the country. To help them decide on the new location they have tasked a staff member with researching current and proposed transport links. It is crucial that they have all this transport information on hand prior to making a choice, as some areas could be ruled out due to ignorance of a new road scheme that will be in place in the near future. AQA AS INFO 2 Course Companion Page 12 of 105 ZigZag Education 2008