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Terms and explanations in EIB

This page provides additional information on some of the terms used in the Evaluation Instruments Bank (EIB).

What is 'evaluation'?

In the context of a drug-related intervention (or programme), evaluation refers to any form of assessment or measurement carried out before the intervention begins, while it is taking place, or after its completion. There are a variety of aspects which can actually be evaluated and a range of different tools to use. The evaluation of interventions and programmes is ideally set up when they are being planned and is always an integral part of a well designed intervention.

What aspects of an intervention can be evaluated?

There are several aspects of an intervention that can be evaluated, each requiring specific data and instruments. Some evaluations comprehensively cover all of them, others only rely on one or two. The different aspects are listed below

Needs assessment and planning

Needs assessment and planning evaluation aims to assess the situation of the target group before and possibly during the intervention. The evaluation can range from assessing  personal status (e.g.  one patient) to environmental social conditions (e.g. an entire neighbourhood).

Why: measure the starting and framing conditions of an intervention, in order to accurately plan and eventually justify it.

When: The assessment is typically made at the beginning, although interim assessments can be conducted to assess the ongoing implementation and to plan adjustments and changes if necessary.

Instruments: Very different data, instruments and sources can be used, from focus groups with community stakeholders or use of local statistics, to in-depth interviews with clients at uptake.

Mediating and risk factors

Mediating and risk factors evaluation– to assess factors that influence and condition the response of the target group to the intervention.

Why: measure how behavioural or personal factors influence the results of the intervention or are themselves altered by it.

When: Often before starting an intervention to find, at baseline, different risk profiles and other influences that may alter the final outcomes. More often, to see how mediating factors change along the intervention and in relation to outcomes.

Instruments: e.g. questionnaires to or observation of the target group, interviews.


Process evaluation – to assess the level of performance of the intervention itself, i.e. the outputs (sessions, materials, structures created, services provided) and implementation (e.g. fidelity, acceptance, retention).

Why: measure the achievement of operational (structure and functioning) objectives for the project itself. See PERK step 5.

When: The assessment can be made frequently (e.g. each session) or once.

Instruments: e.g. questionnaires to the target group (acceptance, understanding), observations by professionals, questionnaires to professionals in the project.


Outcome – to assess behavioural changes in the target group, mostly drug use or surrogates like attitudes or intentions.

Why: measure the achievement of specific (behavioural or health related) objectives in the target group. See PERK step 6

When: Ideally the assessment is made at least before and after the intervention, sometimes more often.

Instruments: questionnaires or observation guidelines to teachers or parents, or questionnaires, interviews to the target group.


Satisfaction – especially relevant in the evaluation of treatment, it assesses whether the intervention is suitable to a specific client.

Why: measure whether the personal needs of a client are met.

When: After or during the programme

Instruments: e.g. interviews and questionnaires


Page last updated: Monday, 24 August 2009