Data and Information

It still has no meaning and is therefore not information The Birth date of Queen Elizabeth II This gives usa ll the elements required dor it to be called ‘information’ Knowledge Knowledge is the ability to understand the relationship between pieces of information and what to actually do with the information. Consider this scenario: Person puts a finger into very hot water. Data gathered: Finger nerves sends pain data to the brain. Processing: Brain considers the data and comes up with. Information: Painful finger means it is not in a good place.

The brain tells finger to remove itself from hot water. Knowledge: Sticking finger in hot water is a bad idea. Knowledge is having an understanding of the ‘rules’ Types of data Data can be stored in many different formats called ‘data types’. When setting up a database or spreadsheet, it is important that the correct data type is selected for each field. This is because the data type will determine what can be done with the data held in that field e. g. sorting, searching, calculations etc. It also can determine the format in which data is displayed e. g. date/time data type will allow you to pick the format of your choice, 14/05/08, 14 May 2008, 14th May 2008 etc. Finally, some data types are able to automatically validate the data being entered. e. g. : When you use a date/time data type then each date will be automatically checked to ensure that it can actually exist.

For example, you would not be able to enter the date 31/02/2008 - it would automatically be rejected or return an error message. A text data type can hold any letter, number, symbol or punctuation mark. It is sometimes referred to as 'alphanumeric' or 'string'. The data can be pure text or a combination of text, numbers and symbols. Telephone numbers need to be stored as a text/string data type because they often begin with a 0 and if they were stored as an integer then the leading zero would be discounted. You are never likely to want to add or multiply telephone numbers so there is no reason to store it as an integer data type. Number A number data type contains numbers.

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An integer stores whole numbers, either positive or negative. Integers however cannot store numbers with decimal places. Real Your numerical data might need to be formatted with decimal places. This means it cannot be stored as an integer number. Instead it is known as a 'real' number. You can specify the number of decimal places that you need. * Currency When you choose to format numerical data as currency then it will automatically be given two decimal places.

However, you can choose to format currency with 0 dp because in some circumstances it would not be appropriate to display the pence. Think of an estate agent, they might sell a house for ? 295,000. It would look daft displayed as ? 295,000. 00. The currency data type also allows you to display the correct currency symbol such as ? Boolean data holds one of two values, for example A Boolean data type is used to answer questions where there are exactly two options, three options would mean it was no longer boolean data. The tricky thing about date / time is that there are so many ways of showing it. And some countries have a different way of representing a date. For example 9/4/94 in the USA means 4th Sept 94 9/4/94 in the UK means 9th April 94 By using a date /time data type, you can choose the format for how you want your data to be automatically displayed.

Another reason to use a date /time data type is that it can provide some basic validation on the data being entered. For example, you would not be able to enter the date 31/02/2008 - it would automatically be rejected or return an error message. Image Databases allow graphical images such as photographs to be stored as a data type. Images are binary files rather than text or numbers which is why a specific data type is required. Different file types such as . bmp, . jpg, . tiff can be stored

Quality of information Things that affect the quality of information Accuracy If the data that you have collected is inaccurate then the information it will produce will inevitably also be inaccurate. Examples of how innacurate data occurs: Questionnaries and surveys * questions might be poorly worded so that users misunderstand them * there may not have been enough people interviewed for any conclusions to be reliable. For example, asking just two people is not likely to be enough Human mistakes * if people are collecting the data manually e. g. ecording answers to questionnaires, writing down instrument measurements, they might make a mistake. Calibration of instruments * if data is being collected automatically by sensors or other instruments then the results could be inaccurate if the instruments were not correctly calibrated at the start of the data collection period Examples of information that would be of little use if it was inaccurate: Weather forecasts Many people check the weather forecast each day so that they can get an idea of what to wear.

People have to have faith that the forecast will be reasonably accurate in order to make decisions. Supermarket prices When you go to a shop you probably know how much money you have to spend. You chek the prices of things you are buying on the shelves and will have an idea of how much it will cost by the time you have reached the till. If the peson entering the price details into the system has accidentally overpriced a couple of items, then this could mean that you don’t have enough money to pay for shopping and have to put something back. Businesses Businesses have to keep accurate records of all the money coming in and all of the money being paid out.

If the accountants make a mistake and dont accurately entera ll of the money received then it could look like the company has not made as much profit that year. Or they havent recorded all the bills so it seems that the company is making more money tan it really is Relevance In order for information to be useful it must be relevant to you. School You have a great deal of information to learn for each of your exams. Each time you go to lessons you probably take a lot of notes and perhaps are given handouts by your teachers to read.

What about if your teachers decided to spend a few weeks teaching you about things that particularly interested them? What they had taught you might have been very interesting to both them and you but it isn't relevant to what you needed at the time. You would find that you had spent a few very precious weeks learning about things that you didn't need to know in order to pass your exam. Weather forecasts Whilst it might be interesting to find out what the weather is like in Florida or Melbourne today, it isn't really relevant to your everyday life.

It won't help you decide whether you need to take an umbrella with you before you leave home in the UK. Doctor’s appointments You might be feeling unwell and want to make an appointment to see your doctor. You phone up the local surgery to find out when the doctor has a spare appointment time. It wouldn't be very useful or relevant to you if the receptionist told you how many appointment times were available to see the nurse. House prices Perhaps your parents might be thinking of moving house. The first thing they would do would be to speak to an estate agent to find out how much their house was worth.

It wouldn't be useful or relevant if the estate agent were to tell them how a similar house in a different part of the country might be worth. Up to date information In order to be useful, information needs to be up to date. In many cases information changes over time and so old or out of date information can be misleading or five you the wrong picture of what is happening. Exams As part of your revision, you have a go at practicing lots of exam questions before the big day and you work your way through the practice papers and model answers that your teacher has given you.

However, some of the papers are over five years old. How useful are the model answers for questions such as 'which storage device would you recommend? ' and 'what is the average size of a hard disk? ' It is well known that things move very quickly in the world of ICT and hardware and software changes rapidly. What was a top-notch computer just three years ago is now probably a very low-spec machine. So the model answers are likely to be out-of-date. Holidays Choosing a holiday can be great fun. And you would probably go to the travel agent to get the latest brochures. Why?

Well, because if you used last year's brochures the holiday may not even be available any more. And certainly the prices would be different. So you need up-to-date information House prices Your parents are still thinking of selling their house. They need an idea of how much their house is worth right now. It would be no use to them being told by the estate agent how much their house was worth five years ago. Completeness In order for information to be useful it needs to be complete. If part of the information is missing then you will not be able to make use of it or make accurate decisions.

Exams Remember those exam papers that you were doing for revision during your study leave? Your teacher wanted you to work your way through them and check your answers against the model answers. What if you were only given the second half of the model answer and the first half was missing? How useful would it be to you? Weather forecast You still want to plan the family picnic for tomorrow. However when you check the weather forecast you are only told what the weather in the morning will be like. There is nothing about the afternoon.

You can't really make a decision just based upon what the morning weather is likely to be. Doctor’s appointment Imagine you are feeling ill and you need to make an appointment to see your doctor. How useful would it be if the receptionist just told you that you could have an appointment at quarter past two? Does she mean today, tomorrow or next week? The information in incomplete. Quality of presentation Information which is presented in a disorganised way or in a manner that is hard to understand will be less useful to you Business data

If you were asked to present some information in a business meeting. It is often better to present it graphically. People find it very hard to spot patterns in a table of data, but the same information presented as a graph makes it very easy. Buying a house Your parents want to buy a new house. It is much easier to pick a house if a photograph was available. Your parents can see instantly if the house would appeal to them and whether they would be interested in finding out more. Once they have decided they like the look of the house they would then want more detailed written information.

However, giving them the written information first with no idea of what the house looks like would make it difficult for them to get an idea as to whether they would like it. Too mucho or too litle detail For information to be useful you need the right amout of detail. There is a risk of having too much detail which makes the information overwhelming and difficult to extract the bits that you want to know about. Or there might not be enough detail in which case you wont understand the full picture. Example: baking a cake Too much detail| Not enough detail|

Ingredients Not only telling you that you need fluor, but telling you all of the different brands of fluor and how the choice of each one would affect the rising of your cake| Ingredients Telling you that you need fluor but not the quantity you will need to weigh ouy| MethodTelling you exactly how many times you need to beat the eggs and for exatly how many seconds you need to fold in the fluor| MethodTelling you to mix the ingredients together but not informing you of the correct order in which to combine them| CookingTelling you the exact amount of minutes that the cake should be baked for every type of oven that is currently for sale| CookingTelling you the temperatura to cook the cake but not how long to leave it in the oven for| Coding of data When you are designing a database system to hold data, one of the first decisions that you will need to make is about how the data will be collected and stored. You already know the term GIGO (Garbage In Garbage Out).

If you collect data and enter it into the system without careful consideration at the planning stage then the output from your system will be of little use. One of the things that you can consider is to code some or all of your data in order to improve the efficiency of your system. What is coding of data? Any system will need to have data collected, entered and stored. One method of storing data is to assign codes to it. This usually means shortening the original data in an agreed manner. The agreement is between the users of the system. This coding scheme could be part of the training of how to use the system, and it could also be documented within the system for new users.

If the coding is completely obvious then there is no such need for formal documentation. For example if a field called 'Gender' has only two values 'M' and 'F'. It should be obvious from the field name that this refers to Male and Female. Example 1 Original data: Monday; Tuesday; Wednesday; Thursday; Friday Coded data: Mon; Tues; Wed; Thurs; Fri Example 2 Original data: Xtra Large; Large; Medium; Small Coded data: XL; L; M; S Example 3 The above codes are fairly easy for anyone to recognise and understand. Some codes however are more complicated. What do you think the following codes might represent? The above examples could be postcodes.

They represent a street name, a particular part of the street and the town where the street is located. Example 4 How about: SK12BN TR14GN These might be a little bit more difficult because the code is made up from different representative parts. Let's have a closer look. The first part represents a piece of clothing, so 'SK' represented 'Skirt' and 'TR' represented 'Trousers' The middle part of the code was the dress size. The final part of the code represented a colour, so 'BN' represented 'Brown' and 'GN' represented 'Green'. You should be able to see from that information that the first code is a size 12 brown skirt. What piece of clothing would the second code represent? Why might we want to code data?

Much of the data that we collected and enter into our systems has some degree of repetition. Speeding up data entry Let's take the example of collecting data about a person's gender. People can be either 'Male' or 'Female'. Whilst these two options are easily understood by all, imagine having to enter the word 'Male' and 'Female' into a system many hundreds of times instead. It is a waste of time and effort because no extra information is contained in the full words compared to a single letter. Increase accuracy of data entry The other issue is that no matter how accurate a person is at data entry, at some stage they are likely to make a mistake and might spell 'Male' as 'Mail' or 'Female' as 'Femal'.

This type of mistake will make any results from your database queries unreliable. Instead of entering 'Male' or 'Female' you could code the data and instead enter it as 'M' or 'F'. Simply having to enter one letter instead of a possible six will speed up data entry. It will also cut down on the risk of mistakes being made with spelling. Use of validation In our example, the words 'Male' or 'Female' have been coded so that they become 'M' or 'F'. When data has been coded it makes it easier to use validation to check if the data entered is sensible. With the example above, the person entering the data could still make a mistake and enter 'S' instead of 'M' or 'F'.

But if you set up validation so that the field will only accept the letters 'M' or 'F' and absolutely nothing else then that should further cut down on possible mistakes. Note that validation can only check if the data is sensible and within reasonable limits, it cannot check whether the data is accurate. Somebody could still enter 'F' instead of 'M'. Less storage space required Every letter that you store in your database system will take at least one byte of storage. If you store 'Female' as 'F' then you will save five bytes of storage space. If the system belongs to a large organisation, there might be many thousands or millions of records stored - simply by coding one field, a huge amount of hard disk storage can be saved. Faster searching for data

It stands to reason that the smaller the size of your database, the faster it will be to search and produce results. Thus by coding data and keeping the size of the system to a minimum the more time you can save in the long run when running queries. Coding examples In our everyday lives we come across many examples of how coding is used to represent data. Here are just a few more ideas: Country names The name of a country can be represented by two letters. For example: Great Britain - GB France - FR Canada - CA Problems caused by coding data Whilst coding data can bring many benefits it can also lead to some problems. Coarsening of data This means that during the coding process some of the subtle details in the data are lost. Look at the image below:

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