3.2 Pilot and small-scale studies

The initial stage of evaluation is an exploratory or pilot study in which the proposed intervention is tried with just a few autistic individuals. Of course, full ethical safeguards must be ensured, and the participants (or parents on participants’ behalf) must give their consent to participation.

If a pilot study suggests a positive effect, a more formal, small-scale evaluation can be carried out. Again this may involve just a small group of participants, who are observed for a period before the intervention, while it is carried out, and for a period of time afterwards. A common procedure for this is a multiple-baseline study. Each participant is observed for a period before the intervention to establish a baseline for the behaviour to be targeted by the intervention e.g. how often the child communicates verbally. The length of the observation period is varied such that the intervention start date is staggered across participants. This makes it easier to ascertain that any change, such as more verbal communications, is due to the intervention itself. If all children started the intervention simultaneously, they might all experience another new factor (e.g. a change of teacher) which could be causing any changed behaviour.