Redesign & Write-up
Heuristic Evaluation Feedback & Design Changes
After receiving feedback from SylViA’s heuristic evaluation (HE), we discussed each violation and developed ideas for improving our interface. The following summary identifies each heuristic violation and our proposed solution(s).
1. [H4 Consistency and standards] (Severity 4) The use of red, yellow, and green on the main thermostat dial to indicate comfort zones is very confusing given that elsewhere in the interface these colors indicate different levels of pricing. We still do not really understand if there is a relationship between comfort zones and pricing, or if you're merely reusing the same color scheme for a totally different set of metrics. If these zones are related to pricing, then what does that beige slice from 65-68 mean?
As a group, we decided to remove the red, yellow, and green "comfort zone" indicators on the round dial and use a single triangle to note each temperature set point. The actual set points will be determined by the user during initial setup (i.e. at the highest pricing - 78 degrees, at medium pricing - 75 degrees, at lowest pricing - 72 degrees). Only one triangle will appear at a time; however, the triangle’s color will change (to be consistent with current pricing). We hope that the simplified display (is less confusing for users while providing a visual cue for why set points change.
2. [H4 Consistency and standards] (Severity 4) The three usage graphs should look the same and just represent different time periods, like when you research stocks and always get the same view for different time spans so you can easily see the comparison. For graphs that are presented as a group, x and y axes must be the same, and preferrably the height would be the same. Unit breakdown can be different for the different time slices. Today's usage graph is too different from 7-day and 30-day to be presented alongside.
With feedback that the "7-day" and "30-day" bar graphs were useful, we discussed ways to keep their current format while separating them from the "today" snapshot (which was a different type of bar graph). Our updated interface separates "Cost" and "Past Usage" information into two top menu selections (tabs). In "Cost", the user will be able to view "Price Forecast", "Today’s Cost", and "Budget" information. "Past Usage" has been simplified to only contain "Last 7-days" and "Last 30-days" consumption summaries.
3. [H6 Recognition rather than recall] Secondary navigation tabs appearing on the bottom is not immediately obvious. It would probably be easier for users if they just popped up underneath the top tab (kind of like DHTML menus) so they would be right there in the user's locus of attention and they wouldn't have to remember to look at the bottom for more options. or [H8 Aesthetics and minimalist design] Bottom tabs are a GUI blooper. or [H2 Match between system and real world] Bottom tabs violate the metaphor of tabbed file cards being stacked on top of one another. Whichever way you categorize the violation, we give it a Severity 3.
Recognizing that we made a blooper, we updated the design to have our secondary navigation bar appear directly below the primary menu tabs. Now, when a user selects "Cost", they will see "price forecast", "Today’s Cost" and "Budget" selections directly below the "Cost" tab.
4. [H1 Visibility of system status] (Severity 3) Temperature, status, setting, time, etc. all appear on the left hand side but it's still difficult to see them all at a glance. These basic important parameters should be made very obvious and grouped together. Also, and I think this is just a limitation of the prototype, but I don't get any feedback when I change the status at the bottom, in that the little indicator in the bottom right corner of the thermostat always says "Away". Also, in the screenshots, when "Normal" is selected the indicator says "Home." And anyway, since one of the radio buttons is selected right there in the same area, the secondary indicator in the corner seems redundant.
In an effort not to clutter the round display with too much information, we decided to create a status bar on the right portion of the display that is "always on". The bar shows time / day / date information to and reports messages.
For the round display, we moved the text which provides feedback on current setting mode to a position just below the current pricing window. The Hold mode is indicated by "HOLD"; Normal by the current program setting (i.e. Home, Away, Mom Visiting); Away (where the user is away for an extended period) is indicated by "AWAY."
5. [H2 Match between system and real world] (Severity 3) Why does it just have two dollar signs and a "Medium Price" label? We think people would be much more inspired to make changes in their behavior if you gave them a concrete dollar figure - i.e. right now electricity costs $5.00 but tonight it will cost $3.00. Maybe establish a base metric to tie this information to - i.e. average cost of running a load in the washing machine right now.
In our "Today's Cost" view, we noted spending information about the most expensive appliances. We updated our price forecast (see image #4 above) to include estimates on what it costs to run highly consuming appliances during varying pricing levels.
6. [H8 Recognition rather than recall] (Severity 3) It's too difficult to match the patterns in the key to the patterns in the bars on the "Today" usage view. We had to keep looking back and forth to figure out what was what.
We modified the "Today" snapshot, using icons and text to show the top electricity consumers and how much it cost the user to run them during each pricing period.
7. [H2 Match between system and the real world] (Severity 3) It's very hard to mentally map the information in the graphs to your real-world consumption of electricity. We particularly feel that a persona like Mabel would not be able to translate this information into meaningful usage improvements. Also, charts and graphs are basically scary for a large portion of the population that is not used to reading them.
Same response as number 6 (above).
8. [H4 Consistency and standards] (Severity 3) We know it's not really built out yet, but the radio buttons underneath the thermostat on the settings screen should match those underneath the real thermostat so we know what state we're setting for.
This violation came from a limitations in our prototyping abilities - the radio buttons under the thermostat (Hold, Normal, Away) are used for overriding the settings schedule, and will look nothing like the settings selection radio buttons (Home, Away, Asleep) on the "Temperature" screen. We tried to make the latter group appear consistent between the "Temperature" and "Schedule" screens.
9. [H5 Error prevention] (Severity 3) The radio buttons for high/med/low on the settings page allow you to select all three.
This was a coding error that has been resolved in this prototype.
10. [H2 Match between system and real world] (Severity 2) Up-and-down arrows akwardly placed, hard to understand their function. We understand that in the real world the dial will be turnable, but for the prototypes there could be a more explicit relationship between the arrows and the toggle on the dial.
To better associate the up/down arrows with the left (round) portion of the device, we moved them to the left side of the thermostat screen. In our physical prototype, the up/down arrows will be removed and the functionality for overriding (changing) the temperature will be in a turn-dial, similar to our low-fidelity prototype.
11. [H7 Flexibility and efficiency of use] (Severity 3) The use of colors as a primary indicator for prices, comfort zones, etc. will not be helpful for color blind users - need different primary indicator like pattern.
We did not feel it was necessary to make any additional changes in this regard since the price indicators and selectors contain the text "LOW/MED/HI" and are also differentiated by number of dollar signs (no image shown).
12. [H2 Match between system and real world] (Severity 2) Seems like the "Today" usage view should start at midnight, not 1 AM.
Time for the "today" snapshot now begins at midnight (see #6 above).
13. [H7 Flexibility and efficiency of use] (Severity 2) You are presenting lots of information even to the novice user. The graphs, for instance, could be present and accessible to the advanced user but simplified summaries of information could be presented by default to accomodate all users.
To present a consistent interface, we decided not to toggle graphs on/off. However, we hope that the changes to the "Today" snapshot are much more useful and easier to read for all users (no image shown).
14. [H5 Error prevention] (Severity 1) Buttons that don't do anything should be greyed out in the prototype (i.e. Messages, Help).
Non-functional portions of our updated prototype have been greyed out (see "setup wizard" in #8 above).
In addition to responses for specific HE comments, we discussed feedback we received after our assignment 5 presentation and made several design changes. Interestingly, much of the feedback from our presentation was consistent with the HE violations noted by SylViA.