1. Suitability Analysis Combining Multiple Maps

2. Suitability Analysis General purpose –To rank potential sites according to suitability for a proposed type of activity Requirements –A set of “factor” or criteria maps, organized to rate sites relative to one or more characteristics –A technique for appropriately combining factors

3. Types of Criteria Absolute –Frequently hard-edged –Often include property ownership/management zones –Often involve legal standards Relative –Typically “fuzzy” edged E.g. “proximity to X” where closer = better, but no absolute distance known in advance –Often involved in trade-offs where values ranges come from specific data within a place Criterion 1 = “Low rent” and criterion 2 = “close to school”

4. Suitable For Whom? Suitability models have a “point of view” –Audience can be human “Affordable housing” Best sites for High-end commercial –Audience can be environmental Best habitat for black bear Most suitable multispecies conservation areas Can be implicit or explicit –But better to be explicit where possible

5. Common Units How do you “combine” –a map representing “meters to nearest road” Units = meters –with another representing “land cost”? Units = dollars Short Answer: find or create common units –Easiest: likert scale “preference” units A range of values: 1 to 5, or 1 to 9 Polar opposites on both sides of range –i.e. “Best”/”Worst”, “Most Suitable”/”Completely Unsuitable”

6. Cautions with Likert Scales –Consistent Application With multiple factors, must make sure that scale consistently applied – example analysis: want to be near streams and far from roads, using 1..9 with 9 = best –Calculate distance to streams, distance to roads –Reclassify stream distance to preference units »Closest = 9 distance = 0 –Reclassify road distance to preference units »Closest = 0 distance = 9 –In other words, may need to “flip” values when reclassifying Doesn’t really avoid scaling issues, just defers –Sensitivity and range in price/distance may be different –Often what’s needed from initial analysis is “range of the possible”

7. Basic Methods (Hopkins 1977) Mathematical combinations –Boolean –Ordinal Combination –Linear Combination –Fuzzy Logic Identification of regions –Cluster Analysis Logical Combination –Exclusions (Relative) Not Used: Nonlinear Combination Not Used: Factor Combination

8. Ordinal vs. Linear Combination Ordinal –All factors have equal weight, added together –Explicit determination of regions and ratings –Involves invalid math operations – should not add values that have a different scale. Linear –All factors have unequal weight, added together –Explicit determination of regions and ratings Both do not handle interdependence of factors

11. Linear Combination I prefer to use weights between 0-1, and they sum to 1.0. –The output range is the same as the input –Easier to interpret Different weighting schemes can be applied –Sensitivity of suitability ranking to a factor –Evaluate different points of view or preferences Different Stakeholders –Integrate the results from different weighting schemes.

13. Defining Weights and Coefficients

14. Many GIS models use empirical values and relationships (ordinal rankings, fuzzy membership functions, etc.) In most cases the hard task is to define justifiable values. The task is a domain area in itself.

15. Defining Weights and Coefficients Methods include: –Theoretical – based on past research Literature Review –Empirical Studies (need a data set) Test of Associations –Public Perception – Important for value-based decisions. –Expert Opinion Need to find consensus Methods include surveys and workshops Delphi Method – consensus without meeting

16. Cost-distance Analysis (Bear, Wolf, Lynx, Wolverine) Step 2: Develop friction surface Cost Model Parameters: Population Density 0 - 10 people/mi 2 1.0 10 - 25 people/mi 2 0.8 25 - 50 people/mi 2 0.5 50 - 100 people/mi 2 0.3 >100 people/mi 2 0.1 Road Density < 1mi/mi 2 1.0 1 - 2 mi/mi 2 0.8 2 - 6 mi/mi 2 0.5 6 - 10 mi/mi 2 0.2 >10 mi/mi 2 0.1 Land Cover All Forest & Wetlands 1.0 Alpine, shrub, 0.8 grasslands grasslands Agriculture, bare0.3 Water, urban, ice0.1 Slope 0 - 20% 1.0 0 - 20% 1.0 20 - 40% 0.8 20 - 40% 0.8 >40% 0.6 >40% 0.6 Cost Model Parameters: Population Density 0 - 10 people/mi 2 1.0 10 - 25 people/mi 2 0.8 25 - 50 people/mi 2 0.5 50 - 100 people/mi 2 0.3 >100 people/mi 2 0.1 Road Density < 1mi/mi 2 1.0 1 - 2 mi/mi 2 0.8 2 - 6 mi/mi 2 0.5 6 - 10 mi/mi 2 0.2 >10 mi/mi 2 0.1 Land Cover All Forest & Wetlands 1.0 Alpine, shrub, 0.8 grasslands grasslands Agriculture, bare0.3 Water, urban, ice0.1 Slope 0 - 20% 1.0 0 - 20% 1.0 20 - 40% 0.8 20 - 40% 0.8 >40% 0.6 >40% 0.6 Road Density Land Cover From: Singleton et al. 2002. Landscape Permeability for Large Carnivores in Washington: A Weighted-Distance and Least-Cost Corridor Assessment. USFS PNW Research Station PNW-RP-549

17. Dephi Method It's a common observation to say that when you get three experts together, you'll often end up with four different opinions. Arguments can quickly become passionate, and disagreement can often become intensely personal and bitter. More than this, in face-to-face discussion, situations of "groupthink" can occur. Here (for example) the eccentric views of early or charismatic speakers can achieve undue prominence as the group seeks to find consensus. This can lead to poor decision making. This is where a technique like the Delphi Method can reach a properly thought-through consensus among experts.

18. Overview The Delphi method is an iterative process for consensus- building among a panel of experts who are anonymous one to another. In its traditional form, extensive questionnaires are distributed to the panel, responses are synthesized and used as feedback to the panel in the next round of questionnaires, for a series of rounds. Experts on the panel do not communicate directly with each other but rather only provide responses to the Delphi administrator (i.e. facilitator). The method was first developed for the military by RAND in the 1940s, and is advocated as a means to achieve an optimally reliable expert consensus.

19. Key Concepts Anonymity. By keeping the process of questionnaires and feedback anonymous, Delphi is intended to avoid undesirable group effects characteristic of face-to-face groups. Critics, however, point out that anonymity could encourage irresponsible responses from panel members. Legitimation. As in survey research, institutional support is often needed to gain access to the needed experts/stakeholders. Since experts are involved, there is often an appeal to advancing the state of research. Likewise, often there is a promise that results of the study will be furnished to experts/stakeholders in a timely manner.

20. Assumptions Potential for selection bias. Output from Delphi is only as good as the experts selected for the panel. Considerable commitment may be required from panel members, and this may affect the composition of the panel. If experts are all professionals in the same area, bias toward a professional agenda may emerge compared to selection of a different type of panel (i.e. stakeholder groups, civic leaders). Potential for administrator influence. The administrator plays a critical role in synthesizing questionnaire responses and providing feedback to the panel. This process is inherently partly subjective and could introduce bias. Important that the administrator stays independent.

21. Dephi Process Group discussion can be done by Internet or conference calls.

22. Dephi Process Participants’ Assessment –Each participant anonymously does an evaluation. –The comments must be quantitative; numbers indicating preferences. –Forms are created for the participants to provide their input.

23. Dephi Process Facilitator computes statistics from participants inputs. Statistics are compiled and returned in a report of the results and prepares a participant’s report. Participant’s report shows how the participants’ input score differs from the group average score.

24. Dephi Process

25. A group usually reaches stability after two and three rounds. Stability is declared when values “stop” changing.

26. Dephi Process Review Select useful participants –Knowledgeable –Representative Anonymous input Facilitator remains neutral Structured debate –Having the right questions is important. –Make sure in the process you ask the question: What is Missing?