Manipulating Data

Manipulating Data

1. Data Capture forms

   • A commonly used data capture form is a questionnaire which allow people to fill them in privatly and in their own time. Useful for when data is wanted to be collected from many people but there is not enough time to talk to everyone in person.
     • have a minimum of printed text/instructions
       • be simple and easy to use
         • be not too long
         • collect the data in a way that can be quickly and easily entered into the computer system
     • provide clear instructions on what to do, how to fill in the form an dwhere to send'hand in the form after it's filled in
       • A form on a screen should:
         • be logically laid out
           • be suitable for use/adjustable so it can be used on different sized monitors
           • not be cluttered
             • relevant to the topic
         • have text that is in a suitable typeface and font
           • have clear instructions
         • have text and images placed in suitable positions to not distract from the topic in question
           • not use colours that are difficult to see or tell apart
             • have a simple and consistant method o fmoving between screens
               • lay off using a background/bright yellow/red background
         • Paper documents should:
           • have room for any headers/footers
           • Leave a gap on the side of the page so if several are stappled together the text is not hidden
           • have gaps where appropriate e.g to be bound together
     • have spaces to be filled in as close to the question as possible
       • be logically laid out so questions follow from one ot another
         • Have the reason for the data capture clearly shown so people know what the data will be used for
   • A good data capture form should:

2. A 'FLAT-FILE' database is one that only contains a SINGLE TABLE of data

3. A 'RELATIONAL' databAse is one that contains TWO OR MORE TABLES of data, connected by LINKS called RELATIONSHIPS

4. Repeated data in a database is generally considered as a bad thing because it WASTES SPACE in the database and takes TIME TO INPUT (as you are typing in the same data repeatedly where mistakes an be made and can take ages to update.

5. Database- an organised and structured way to store data

6. A feild is used to store one peice of information in the database

7. A record is a collection of all the fields for one particular person or thing

8. A table is a collection of records of the same type, so a student table in the school databse would contain the student records

9. Datatypes

   • Text/Alphanumeric- allows only numbers and letters
     • Integer- whole number
       • Boolean- allows one of two options
         • Date/time- date or/and time
       • Autonumber- computer generates a unique number for each record in the table
         • Numerical- only numbers
         • Real number- any number including decimals
     • Currency

10. Ascending- smallest to biggest or earliest to latest or A-Z

11. Descending- biggest to smallest or latest to earliest or Z-A

12. Veriification- checking that the data has been entered correctly.

    • Double entry of data, visual check, hash totals and batch totals

13. Validation- Checking that the data entered is sensible

    • Range check, format check, length check, presence check. check digit

14. Foreign key- A foreign key is used to link tables together and create a relationship. It is a field in once table that is linked to the primary key in another table.

15. Data Capture

    • Pros: Fast method of inputting data (10,000 forms per hour), only one computer needed to collect and process data, more accurate than data keyed in by a person, decreases investment cost since only one computer is needed to store the data
      • Optical Mark Reader- OMR interprets the pattern of marks and sends the results to the computer for storage, analysis and reporting
        • Barcode scanner- electronic non-contact device which is able to read printed barcode and transfer the data captured by them to a computer to make sense of it.
          • Pros: Can find out details of products sold and prices in shops by scanning a barcode with the scanner,any price change only needs to be made on database and not every product packaging/scanner, quicker to scan a barcode than typing code manually as human errors could occur, can get portable barcode scanners, hardy any situations where scanner does not find the right object
            • Cons: limited range it can reach, dirty/ripped barcodes cannot be recognised easily by the scanner, may have to keep re-scanning item if the scanner is not positioned at the right angle.
          • Microphone for speech-to-text- can be used to pick up sound and input it into a computer
            • Scanners- can be used to convert images or text on paper into digital images to be used on the computer
              • Magnetic Strip Reader- hardware which reads information encoded on the magnetic stripe that stores personal details e.g. account number ( up to 60 characters) magnetialy.
                • Sensors- used to detect physical quantities outside a computer such as light,temp.,pressure.
                  • Pros: sensors can monitor information constantly, readings taken from sensors are usually more accurate than ones taken from humans, no need for humans operate the sensor, can detect physicalqualities that are harmful in the area
                    • Cons: faulty sensors can give incorrect results, some sensors are epxensive
                  • Chip and pin- insert the card into the card reader and the reader makes a connection with the chip. A PIN is then entered to confirm the card belongs to you
                    • Pros:secure method, can store more than a magnetic strip reader
                      • Cons: risk of fraud, people could forget their PIN
                    • Biometric devices- a computerised method used to recognise a person from their unique physical (e.g.fingerprint/face) or behavioural (e.g.voice/signature ) characteristics.
                      • RFID (radio frequency ID tags)- commonly used on expensive products which are highly desirable (small tracking devices).
                        • Pros: Can help spot stolen items as when a product is scanned at the till the tag is removed/deactivated by the cashier.If it has not then it will alert security when taken out of the shop unpaid for, can help find products that have been put back on the wrong shelf instead of its correct space
                          • Cons: size and wight of the tags is more than a barcode system, if tags get damaged they cannot be tracked, tags can only be read within a specified range, more costly than other identification/tracking systems
                      • Pros: increases security, no need for people to carry ID cards, harder for people to forge/make duplicate copies, more available and accesbile, makes identifying people much easy as you get a almost instant results, more effetive
                        • Cons: false rejection as errors could occur, false acceptance as criminals could find a way round biometric devices, security issues- who is handling data kept about individuals?, expensive technology
                • Pros: simple fo rpeople to use((little/no training required), cards are inexpensive to produce, data on the cards can be altered if necessary, security is improved by the use of PIN numbers to confirm that the person is the rightful card owner, cards are quite robust
                  • Cons: very limited storage capacity for data, data can be destroyed easily by strong magnetic fields, not always secure as thieves can obtain the card and read the data on it, a thieve could clone the card
              • Pros: flatbed scanners very accurate and produce a reasonably high quality image,one scanned images can be stored digitally and then manipulated with graphic applications/included on electronic documents,specialist scanners can convert old material like 35mm negatives into digital filed
                • Cons:images produced by scanner can take up a lot of memory space when stored in a digital form,imageslose some quality in the scanning and digitalising rices, the quality of the final image is dependent on the quality of the original,there may not be any value in the original image
            • Pros: can dictate speech inserted into text quicker than typing it into the software,save times for slow typers/people who are disabled/cannot use conventional keyboard,the program used can be compatible with other software,many commands can be dictated by speaking into microphone
              • Cons: could interpret words incorrectly if used to change speech into text,costs more than typing on a keyboard,need a quiet/silent location otherwise words said in the microphone may not be understood
      • Cons: If marks don't fill spaces/aren't dark enough pencil they may not be read correctly, only suitable for recording one out of a selection of answers not text, OMR reader needed answers to be prepared on forms which will all be identical to each other not blank sheets.

16. A relationship is created when there is a link between two fields (whhere they share the same common field)

    • Entity relationship diagrams- one-to-one relationship or one-to-many /many-to-one relationships