the desing phase factors to be considered when diesiing the input reuqairments,”having established what the systme needs to produce to nmeet it;s goals the next are of interest is establishing what data needs to be obtained to peoduce that output. THe design of the input is vital to the successful creation of a computer system. Put simply m the input must be collected from the various sources with a minimal amounf of errors, and with the greatest possible speed. A common term used to describe data entry is GIGO-garbage in, garbage out this expression highlights the importance of input design of the quality of the program produced . THe final output will only be accurate as the data put into the system and the quality of the data will be partly determined by the quality of the design of the collective methods. There are a number of techniques that a good programmer will use to ensure that the data they cfollect is of the best quality possible they will limit the opportunities for the user to enter the wrong data. and will ensure the user does not have to enter data there. When desigining input, the programmer should: Identify duplicate data-effecient program design requires that the program only collect and store each data element once. Programmers should analyse the data requirments and identify where data is used more than once and ensure it is collected just once. It is important to do this- while it may be easier to collect data more than once, rather than create highly complex data structures, this approach compromises the integrity of the infgormation produced as it allows for more input errors and the erection of conflicating outputs. Identify methods of reducing input errors- when collecting data, the programmer should make use of as many of the features available to ensure that the data being collected is as free from errors as possible. This can be achieved through the use of features like deop down boxes, radio buttons, check buttons, etc. That limit the user to selecting from pre-defined “”correct”” options. By carefully constructing input screens, it is possible to limit the number of areas the user can enter invalid data. Identify data validation checks while it is possible to limit the users choices to pre-defined choices it may not always Be possible or practical to do so an example would be post codes. While all postcodes are pre-defined, there are so many of them it would not be possible to list them on a screen, so another method must be employeed to make sure the data is accurate, Writing code to check the data is accurate can do this. For example the postcodes could be checkeed to see if they fall withing the expected range for the state given. WHile this relies on the user to input correct data, it does reduce the amound of incorrect data the system collects. Input screen/ method design- thought needs to be given to the actual dsign of the input collection screen or methods care needs to be taken to ensure the screens that collect the data are arranged in an attractive and logical manner
if data is to be from a form then trhe data collection screens should follow the general format of those screens to make data entry easier and therefore less prone to errors.”