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The design is very efficient, using the minimal amount of menus and screens to input a receipt. Also, when presenting expenses across different categories, the interface shows the user all the relevant information in one graph, saving him a step of typing a specific query.
Error Prevention
This design allows easy error prevention using the "retake" button. With just one click, the user can recover from an error. Also, re-editing a receipt after it was inputted is pretty easy and straight-forward.
Design 2
Learnability
Most of the options of this design are derived from existing designs of many common smartphone menus. Taking a picture of a receipt and browsing through old receipts is similar to the iPhone's camera interface, and entering and editing receipt and report details are similar to its settings menu. This aspect of the design makes it very learnable for smartphone users. The other elements that do not have a parallel in common menus or applications are sufficiently documented, with the buttons stating exactly which action should be taken. One aspect in which the user will have trouble learning the interface is navigating between the different screens. It is not always clear which button will lead to which screen and which receipt/report the user is currently looking at.
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This design does not prevent the user from making most errors. The different fields in the receipt categories do limit the types of input a user can insert, but common mistakes will probably include mis-categorizing a receipt, entering the wrong amount, or attaching the wrong picture to the receipt. Mis-categorizing a receipt or entering the wrong amount can be fixed be fixed by looking up the receipt item under the report and editing it, but attaching the wrong picture would force the user to delete the receipt entirely and create a new one.
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