Guidelines for trust interface design for public engagement Web GIS

Figures & data

Figure 1. Trust and online trust components (Skarlatidou et al. 2011a).

Table 1. Trust cue design dimension

Trust cue design
1. The logo of the site operator or provider should be clearly visible on all pages (including the GIS component) and should be of high quality
2. Copyright and data issues (e.g. the data provider) of maps should be clearly visible (ideally below the map)
3. Provide external links for additional information
4. When external links are provided, the operators should regularly check each link provided. Messages such as ‘We are not responsible for the content’ may decrease trust
5. Contact details should be easy to find (ideally as a menu item)
6. When additional services such as the ‘Sign up for flood warnings’ in the WIYBY example are used, it is essential to clarify how user information is treated and that it is not passed on to third parties
7. A blog that connects and creates a network of people increases trust
8. Information about data accuracy and how the maps were constructed is essential (ideally located below the map)
9. Provide a map tutorial (ideally below the map)

Figure 2. PE-nuclear-radioactive waste page.

Figure 3. Suitable site for disposing of nuclear waste in Cambridgeshire.

Table 2. Post-test questionnaire used to evaluate trust-oriented interface design: example of legend item

Legend item
How influential is the legend on your decision to trust an online map?	Which one of the two interfaces do you like the most?	Which one of the two interfaces do you trust the most?	Please make any suggestions/comments
1. Not at all	Interface 1	Interface 1
2. Relatively important	Interface 5	Interface 5
3. Very important

Figure 4. Participants' most and least trusted interfaces (affective trust stage).

Figure 5. Participants' most and least liked interfaces (affective trust stage).

Figure 6. Relative importance of trustee attributes.

Table A1. Trust guidelines for user interface

	Graphic design	Structure design	Content design	Functionality design
User interface	1. The menu should match popular menu visualisations 2. The graphical user interface elements should offer affordance and should comply with Internet standards (e.g. visualisation of links should match expected colour codes and visualisation patterns) 3. The visualisation of interface design features should be consistent throughout the Website 4. Use high-quality graphics to impart professionalism	1. Group the menu and content in a logical manner (information should be easy to find; the menu should effectively communicate Website's contents) 2. Provide hyperlinks to increase accessibility of information from different pages 3. Textual information on different pages should be grouped effectively and should be relevant to the context 4. Titles, headings and subheadings should be meaningful and should help with skipping paragraphs (especially if textual information is too long) 5. Provide a site map 6. Provide a menu item for the GIS element	1. Vocabulary should be easy to understand or should be explained 2. Explain scientific terms and provide interactivity options (e.g. hyperlinks, pop-up messages) so that people can refer to them easily 3. Run frequent updates 4. Error messages should be communicated in non-technical terms 5. Support both domain experts' and novices' needs (e.g. in case an expert user expects additional information, provide external links previously inspected for reliability purposes) 6. Provide guidance and documentation for system's novice and expert users	1. Fix broken links or ‘Not Found’ pages

Table A2. Trust guidelines for GIS component

	Graphic design	Structure design	Content design	Functionality design
GIS component	1. Colour combinations should be effective; use distinct colours (e.g. red/blue/green or alternatively shades of blue; consider colour deficiency)	1. Always provide a legend to explain map features (even when the map is considered to be simple)	1. Information about spatial features should be easy to access from map page	1. Ensure browser compatibility
	2. Communicate map results effectively (avoid overlapping symbols; instead use different colours or shapes and transparency levels) 3. Map size should be larger than 400 × 600 pixels 4. Selected objects should be easy to identify 5. Base maps should be of high quality and relevant to the context of the application 6. The map results should stand out from the base maps (do not use the colours of base maps to visualise additional information) 7. Scales should be chosen so that each provides high quality and useful maps 8. Legend should be of high quality and help interpret the map and all of its features. It should be simple and provide information of both map results and base map features	2. Legends should not block the map 3. Search box should be immediately visible from map page (ideally located next to the map)	2. Generalisation should not lead users to doubt map accuracy or make maps difficult to read 3. More than four scales should be provided and should be chosen to support and provide meaning to the tasks 4. The information on base maps should be considered separately for each map scale so that maps are not cluttered 5. Provision of information about spatial features should support both experts' and novices' needs and expectations 6. Information as to how the maps were constructed should be always provided 7. Provide help and documentation/instructions/or tutorials about GIS tasks 8. Provide information about data accuracy issues (ideally located below the map) Note: Information about the data, maps and tasks should be visible on the map page (e.g. information should be below the map; links that direct users to pages where this information is located should be next to the map)	2. Map functionality should be consistent (at all scales) 3. Map functionality should be unique (do not provide more than one function for the same task) 4. An undo or cancel feature should be provided, if the application supports complex tasks 5. Ensure that map tools can be easily recognised (or else provide a tutorial, FAQ section visible from the map page) 6. Functionality tools should be predictable 7. Provided functionality should support users' needs and expectations

Skarlatidou , A. , Haklay , M. and Cheng , T. 2011a . Trust in Web GIS: the role of the trustee attributes in the design of trustworthy Web GIS applications . International Journal of GIScience , 25 ( 12 ) : 1913 – 1930 .

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