Interface Design Inputs and outputs data flows to and from external entities data flows into and out of processes that are manual or not fully automated User interaction how the user communicates with the system mechanisms for navigation feedback control security etc I O Design Issues Audience What tasks are they doing What level of detail do they provide or need How technology literate are they How much time will they spend with the input or output How often will they provide the input or generate the output Media For a given input or output you must decide whether it should be paper or electronic or something else accessibility of computers to system users portability expected life expected frequency on line or batch timeliness required underlying hardware and support software Designing Layout Consistency is key Throughout the system use the same colors for the same purposes use the same highlighting or borders to convey similar meanings use terminology and acronyms consistently put similar pieces of information in the same location Designing Layout cont Color and highlighting First of all CONSISTENCY Second Moderation Best combination black on yellow Worst combination red on green Strong techniques such as blinking and audio should only be used in the rarest occasions and then only temporarily Designing Layout cont Bias Your design outlives you Sorting more attention is given to things listed first Ranges make sure they re the right ones Graphics color and appropriateness scale user training User customization a double edged sword User involvement required Designing Layout cont Use plenty of white space Plan for screen and page breaks Include administrative information Top to bottom left to right Use Submit and Clear buttons Input Accuracy and Efficiency Layout top to bottom left to right group related items together separate titles from body from instructions clear titles and captions don t be stingy with white space Eliminate typing checkboxes pull down menus icons default values Checking accuracy check reasonableness of combinations predefined acceptable values check for proper format check for missing values Assessing Usability Can assess an entire system for usability or just one form or report User involvement in usability assessment is necessary Some measures learning time user speed user accuracy user s ability to remember system operation subjective assessments Interaction Methods Command language necessary on some older systems but pretty much outdated Menus most common at this point drop down pop up Forms good if the interaction consists of specific pieces of information Object based icons intuitive and space efficient but can be designed poorly Natural language not there yet Conventions When designing the overall user interface you must decide on some conventions to be used throughout the system e g what different colors mean what certain symbols mean navigation mechanisms terminology artwork and logos Navigation Always make the next step clear Don t overly restrict the user s movement No dead ends Navigation mechanisms should be used consistently Let the user know or choose consequences of leaving a form Dialogue Diagrams Map out the overall user interaction with the system Represents the expected use of the system Doesn t necessarily capture all possible scenarios Represents the inputs and outputs and the order in which they will be accessed Dialogue Diagram Example Perfect Pizza 0 Main System Screen 1 New Customer Screen 2 0 2 New Order Screen 3 4 0 5 Weekly Sales Report 0 4 Cook Order 3 Delivery Instructions 3 0 4 0 User Feedback Status always let the user know what s going on don t let no news be good news Prompts tells the user what is expected of them convey as much guidance as possible within reason Errors and warnings convey importance suggest resolutions be careful of jargon Providing Help Provide different levels of help Test a lot under realistic conditions Use a variety of terms to help in searching Starting point should always be visible Navigating help should be simple Security Often not considered part of user interface design Helpful to choose security mechanisms at user interface design so that the user s role in security can be integrated into the interface Mechanisms Views and authorization rules restrict access according to who the user is Authentication schemes establishes identity of user Encryption procedures protects against access from outside GUIs GUI Graphical User Interface Allows different parts of user interface to be active at the same time Complicates dialogue design Common components data entry boxes check boxes radio buttons drop down menus or list boxes command buttons message windows tab control dialog boxes Special Considerations for Web Interfaces Test using different browsers Use and reuse other sites as examples Navigation no dead ends Form is not enough Plan for maintenance Using a metaphor can be helpful Use keywords in text Beware of background patterns Home page should load quickly