13. Guidelines for Input Screen Design Data Entry Activity Guideline for Effective Design Data Entry Avoid requiring entry of data that can be computed, derived, or retrieved from an existing on-line source. Field Defaults Provide relevant field value defaults where appropriate. (i.e. assume current date for invoice date field) Required Units Clearly indicate the desired unit values for data entry fields. (i.e. pounds, inches, dollars, tons, etc.) Data Replacement Provide “intelligent character replacement functions by suggesting a completed entry after the user has typed the first few characters. Field Captions Provide information field captions such that the end user can determine the appropriate data to enter. Field Formatting Provide explicit formatting examples where relevant to indicate the proper method for entering data with required embedded symbols or a specific sequence. (i.e. social security number, 999-99-9999 or date, mm/dd/yyyy) Data Alignment Provide automatic alignment for data entries using left justification for text and right-justification or decimal justification for numbers. End User Help Wherever possible, provide context-sensitive help mechanisms and hot-key access to help facilities.
14. Guidelines for HCI Dialogue Design Dialogue Guideline Explanation Be consistent All dialogues should be consistent in action, sequence, required keystrokes, and terminology. Enable user shortcuts End users should be allowed to take advantage of shortcut keys or macro commands wherever possible and appropriate. Provide relevant feedback Feedback should be provided to the end user for every data entry action. Allow for closure All dialogues should have a clear beginning, middle, and end. Provide error-handling guidance All possible errors should be captured by the system and reported back to the end user in a manner that allows for correction or provides suggestions as to how to proceed. Allow reversal of action Wherever possible, end user actions should be reversible and data deletion should not occur without explicit confirmation from the end user. Provide user control The dialogue should allow experienced users to feel in control of the system and should facilitate inexperienced end users by allowing the user to take greater control of the process as experience develops. Reduce cognitive load Dialogues must be simple to use and must provide for a minimum cognitive load on the end user.
15. Input Validation Controls Input Control Mechanism Explanation Data Typing Data should be checked for proper type (numeric, alphabetic, or alphanumeric) Reasonableness Data should be tested for reasonableness of value given the situation (negative interest rates not allowed, appropriate rate of pay for specific employee category) Expected Value Data should be checked against some expected value where appropriate (model of automobile should match make of automobile) Missing or Required Data Fields should be checked and flagged for missing data that is deemed necessary to complete the data entry process ( has a quantity been provided for every item on the purchase order?) Check-Digit Calculation Check digit calculation should be conducted upon appropriate field entry to insure proper account number or other numerical data accuracy. Data Format Data should be checked against any required format or template to insure proper entry (999-99-9999, (999) 999-9999, 99AAXX9AX) Value Range Data should be checked against any known or established value range (two-letter state codes should come from acceptable list of codes) Entry Size The number of expected characters should be checked where appropriate (is the social security number exactly nine digits?) Allowable Entry Data should be limited to a range of allowable entries and this range of choices should be provided to the end user, where appropriate)
16. Check Digit Calculation Process Example Number each digit of a numeric entry according to place value from either right or left beginning with 2. Assume account number of 34763 : 34763 23456 Multiply each digit in the numeric entry by its assigned place value. 3 4 7 6 3 x 2 3 4 5 6 6 12 28 30 18 Sum the result of the multiplications. 6 + 12 + 28 + 30 + 12 = 94 Divide the sum by the modulus number (usually 10 or 11) Assume a modulus number of 11 : 94 / 11 = 8 remainder 6 Subtract remainder from modulus number and append check digit to numerical entry. 11 – 6 = 5 (check digit) 347635
