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We chose to put this information into the home page because it is the information any user (with the exception of a user whose goal is pure speculation, which we do not believe will happen) would wish to see before doing any actions: what midnights s/ he is assigned, what midnights s/ he is trying to trade for, and what midnights s/ he has successfully traded. By pulling it all together and presenting it in a compact manner, the new design allows for two distinct and common tasks: a user at home can analyze his /her current situation and decide to take action from there, all without navigating to a different page; or, a user on-the-go can quickly glean updates. The old interface would require a considerable amount of navigation to achieve the same tasks.
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First of all, we changed the way MidnightExchange ran in order to more accurately reflect a typical exchange. Instead of showing all the bid/asks for a midnight, their values, and their proposing parties, we chose to display only the best bid/asks (thus, the highest bid and lowest asks) and to preserve anonymity. This was an important and correct decision. The typical rational user need not see all the bids/asks on a midnight if s/ he is seeking to either buy the labor for it, or sell his /her labor for it; rather, s/ he only wants to see the best deal that s/ he can get. Anything extra information would detract from both efficiency (more reading/scrolling) and visibility (harder to distinguish the important information from the information that the server only needs to know).
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The confusion arises from the fact that a user who buys labor for a midnight is no longer assigned to it; thus, superficially, it seems that the user has lost something that belongs to him/her. The rationale is that chores are un-wanted; thus, you have to pay someone to give them your chore.
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We promoted user control and efficiency by allowing users to initiate trades from any page. Users can initiate trades on midnights they are assigned to from their home page; they can can initiate trades on any midnight from the schedule and quotes page; finally, they can initiate trades on midnights on their watchlist from the watchlist page. We chose to offer such functionality because it was a good balance between simplicity and user control.
The user accesses the home page for one of two reasons: he has just navigated to MidnightExchange in his browser, or he wishes to see only the midnights and trades pertaining to himself. Although the user could have the most control if we allowed him to trade for any midnight, doing so would detract from visibility and efficiency. Users on the home page will likely care most about trading away their assigned midnights, if at all; were we to allow them to trade for any midnight on the home page, we'd have to implement some way for the user to choose from the very large selection of midnights. The home page does not have a table interface like the other pages; thus, any implementation would take up extra room and require the user to do more work to find the midnights he is interested in. The schedule and quotes pages are only one click away and offer full functionality.
We allow users to trade for any midnight on the schedule and quotes pages because the tables therein lend themselves very well to such a task. Organization has already been explicitly defined by the table structure. The only work necessary is the visual affordance for clickability.
Finally, we allow the user to trade for midnights on their watch list from the watch list page because that is why the watch list page exists.
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Implementation
Describe the internals of your implementation, but keep the discussion on a high level. Discuss important design decisions you made in the implementation. Also discuss how implementation problems may have affected the usability of your interface.
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