III PARTE

For a child injury prevention education programme to be successful, at least three

hierarchical components are necessary (Waters et al., 2001). First, the children should be taught a target safety message in the programme. Second, the required knowledge should be conveyed by the programme and this knowledge gain and retention checked. Thirdly, use of this knowledge outside the school setting should be taught by the programme so that children have an appreciation of what to do should they encounter hazardous chemicals in normal settings.

6.2.1 Results

Page 179 of 308

teaching the safety message, the term definitions and the symbol meanings.

More individual positive reinforcement (for example praise) was used and more individual competition seen when using the traditional teaching method, as was the case in the teaching to learning styles part of the experimental group. In the active learning part of the experimental group however, there was more group reinforcement and group competition.

6.3 Evidence

The term intervention can relate to a curriculum, stratagem, educational practice or programme (Johnson, et al., 2004). In order to facilitate educational practitioners in the task of distinguishing educational studies that are supported by empirical evidence from those that are not, the United States Department of Education produced a report in 2003 written by Boruch, et al. (2003) This report defines the parameters to distinguish between the various levels of evidence. In fields such as medicine and psychology the ‘gold

standard’ for the evaluation of an intervention’s efficacy are considered to be well designed

and implemented randomised controlled trials. Studies that, to determine the effects of the intervention, randomly assign individuals to a control group or an intervention group are termed randomized controlled trials. The results of studies can be classified into various evidential levels defined as contributing no evidence, possible evidence and strong evidence of efficacy (Boruch et al., 2003).

6.3.1 Strong evidence

It is generally accepted, and there is credible evidence to suggest, that randomized control trials are, relative to other study designs, superior in measuring the true effect of an

intervention when properly designed and implemented. A school based educational study must use well designed and implemented randomised control trials in two or more typical

Page 180 of 308

school settings. Therefore, there are no systematic differences, in any characteristics (unobserved or observed), except one, which is that the control group does not participate in the intervention and the intervention group does participate. The process of randomly assigning individuals to either a control group or intervention group ensures this. Therefore any outcome difference between the control group and intervention group, assuming the trial is properly carried out, can, with confidence, be ascribed to the intervention which is not affected by other factors (Boruch et al., 2003).

6.3.2 Possible evidence

Possible evidence can be established by several types of study design. For example randomised control trials where they fall short of the strong evidence criteria even though the quantity and quality of evidence is good. Another example is comparison group studies when the comparison and intervention groups are matched closely in various

characteristics such as demographics, academic achievement and a range of other characteristics. Valuable in generating hypotheses about ‘what works’ are well-matched

comparison-group studies, however randomized controlled trials need to be used to confirm their results (Boruch et al., 2003).

Relative to the ‘gold standard’ of randomized control trials comparison group designs are

considered to produce valuable conclusions if the control group and intervention group are closely matched in such factors as prior test scores, demographics,methods used to collect outcome data and time period in which they are studied. The overall conclusions, on whether or not an intervention displays efficacy, yielded by such well-matched

comparison-group designs are usually correct. Establishing ‘possible’ evidence regarding an intervention’s effectiveness can be achieved using well-matched study designs. These

Page 181 of 308

types of study have a valuable role to play, especially in education, allowing the generation of hypotheses that can be confirmed using randomized control trials. The study is

designated as not being supported by meaningful evidence if the criteria for strong evidence and possible evidence discussed above are not met (Boruch et al., 2003).

When an intervention is not supported by ‘strong’ evidence the question then arises of whether it is supported by ‘possible’ evidence. This depends on the quality of any non-

randomized studies that have been done and a consideration of any flaws in the study design, however this can be a difficult conclusion to reach and relies on considered opinion.

When trying to decide whether the intervention is supported by ‘possible’ evidence there

are many factors to consider. The comparison and intervention groups should be closely matched on a number of factors. In the domain of education, studies should have two groups closely matched relative to academic achievement and prior test scores.

Characteristics such as gender, ethnicity and age should also be closely matched. The study time period should be approximately the same (for example the children in both groups are in the age range 7-11 years old and are in the same academic school year and not sequential years). The outcome data collection method should be the same, for

example both groups being administered the same test in the same way.

Children who had the choice to participate or not in an intervention should not be included in the control group as they may differ, systematically, in characteristics such as their enthusiasm, and other factors, relative to those who chose to participate. The variation in enthusiasm and other factors could skew the estimation of the study’s effects. The control

Page 182 of 308

group should be composed of participants who were not given the option of whether to participate in the study. The lower the attrition rate the more confidence can be placed in the results and studies should have valid outcome measures. It is essential that tests for statistical significance are reported.