Pastakia Principle

The RIAM method is simple to use and based on an empirical principle that has been in use for over 30 years.

The Pastakia Principle is the basis for the RIAM method and is summarised:

All decisions are intrinsically made up of at least two parts, with judgements made in each part. The judgement/s in the first part will determine the result of the decision, the judgement/s in the second (and subsequent) parts add value to the decision.

In RIAM the scoping exercise will set out different components under each of the 4-Circles. These components are then assessed by criteria based on the Pastakia Principle.

In RIAM only two sets of criteria are assessed, as Group A and Group B,

Group A

Criteria that are importance to the condition that can individually change the score obtained.

  • A1. Importance of the condition (spatial aspects of change)
  • A2. Magnitute of change/effect (size/scale of change)

Group B

Criteria that are of value to the situation that should not be capable of individually changing the score obtained.

  • B1. Permanence
  • B2. Reversibility
  • B3. Cumulative/Synergistic

Each component is assessed independently of all the others, and so each becomes a unique record of the assessment.

The RIAM scores attributed by the assessor to each criterion in each group are set out in RIAM, and the selection of each score can be recorded in the matrix to justify the score and allowed for review and updating in the future.

The Group A criteria are multiplied together, the Group B are added together. Then the product of Group A is multiplied to the sum of Group B, to give an Environmental Score (ES).

(A1 x A2) x (B1 + B2 +B3) = ES

The same Environmental Score can be generated from more than one combination of criteria scores, so for this reason the ES is placed into a final value (Range Value) that defines its impact.

It is important that the Range Values (RV) are used as the final RIAM result as this specifically defined the assessment of the condition. It is not desirable to try and add together ES scores, or in any way aggregate them or give attributes to a score as each is an independent assessment.

The Range Values have been defined to place the ES into specific bands describing the assessed impact. The alphabetic RV scale allows for a clear result from each component to be shown.

Recording the reason for score choice in the matrix, ensures full transparency of the RIAM assessment.