# Personalizing Environmental Awareness through Smartphones Using AHP and PROMETHE II
## 3 Defining MCDM Based on User Model  
### Description of Criteria  
The main characteristic of an MCDM model is that every alternative action is evaluated on the basis of several, often contradicting, criteria. These criteria are not equally important in the reasoning process of selecting which action seems better. Therefore, a weight of importance is calculated for each criterion. The multi-criteria decision-making methods differ in how the criteria weights are computed; however, many methods do not employ a predefined method for the calculation of the weights of criteria. For example, PROMETHEE II does not employ a well-defined means for the calculation of the criteria's weights. On the other hand, AHP has a very well-defined method for calculating the weights of criteria and as such the particular MCDM theory is used in the following steps.  
After having defined the main goal of the MCDM evaluation, which, in our system, is to evaluate the alternative pieces of advice and select the one that seems to fit better to the interests and needs of a user in order to help him/her reduce his/her environmental footprint, the next step involves setting the set of criteria.  
In order to define the criteria that are taken into consideration while evaluating environmental advice, and since the set of criteria had not been formed before in a similar system, we conducted an empirical study. In this study, six environmental experts (two experts in sustainable development and biodiversity, two experts in waste management, and two experts in climate change) participated, and the criteria that all experts agreed were essential for evaluating the alternative advice are presented below:  
1. C1: Compatibility of current location: the system checks if the location of user is in urban environment, sea, mountain, river, lake, or plain country and searches the: 1. Compatibility of subject with urban environment 2. Compatibility of subject with sea 3. Compatibility of subject with mountain 4. Compatibility of subject with river 5. Compatibility of subject with lake 6. Compatibility of subject with plain country  
In view of the above, the compatibility of the subject with the current location of the user is calculated as a value to this criterion. The values are \(0<\text{C1}<1\).
2. C2: Compatibility with the environment of residence: Checks whether the subject is compatible with the environment where the user's home is. The value of this criterion is very high if the user is at home and low if the user is away from home. A subject concerning the environment where s/he lives is very important and must not be overlooked, but if s/he is away from home, it is possible that other subjects have higher priority in the particular moment.
3. C3: Compatibility with user's habits: This criterion reveals whether the alternative advice is compatible with the user's habits as these are stored in the user model. For example, a piece of advice that is relevant to waste management is higher if the user already has some habits related to this, e.g., s/he recycles.
4. C4: Compatibility with user's interests: This criterion reveals whether the alternative advice is compatible with the user's interests as these are stored in the user model.
5. C5: Compatibility with user's needs: This criterion reveals whether the alternative advice is compatible with the user's needs as these are stored in the user model. For example, the user model reveals that there is great need for economy in natural resources, so the value of this criterion is higher for advice related to this need.  
6. C6: Compatibility with age: Users, according to the six human experts, were categorized into four age groups: 1. <18 2. 18-30 31-60 4. >61  
The value of this criterion shows the compatibility of the alternative advice with the age group of the user.
7. C7: Compatibility with season: This criterion shows whether the piece of advice is compatible with the current season or the current month.