The scale of the work has to be more or less standardized (to the extent possible) and mapping. Ideally, all variables would have the same scale in order to overlap some elements with others. The scale of work is somehow determined by the budget and deadlines that have to deliver work and to carry out the project, although sometimes they can be determined after selection of the scale. It is important that this first analysis detects the elements and factors most sensitive and meaningful to the EIA through the means mentioned above. The variables of the environmental inventory. The selection of variables in the inventory (which, let's not forget, have to be the most significant factors and are subject to change due to the project) must meet the following conditions: Significance. Follow others, such as ALS, and add to your knowledge base. The variables have to be significant for our study.

Operability. The variables have to be easily used and integrated into the review process (in this sense we can classify the variables into two types: those that are the result of integrating simpler ones and those that are self-explanatory). Ease of data collection. Accuracy. Keep in mind how accurate we can achieve as the variables that are within the inventory. Model. Although not a common feature within the variables that are usually handled, knowledge of system operation (which, ultimately, is what interests us at this stage) can be transformed into the possibility of predicting with greater or lesser reliability the future behavior of the same (hence the importance of accuracy in our measurements).