Conferencias basadas en el archivo del Dr Comas

The means were then plotted (figure 17) for all results pre-test, immediate post-test and 1 month post-test. Both school 1-control and school 2 made statistically significant pre-test to post-test gains. The gain for school 2 pre-test to immediate post-test was larger than school 1 as school 2 gave a lower pre-test result but achieved about the same post-test result. School 1 gained 34.8% and school 2 gained 43.3%.

T1 comparison

Un-Paired T-Test

Unpaired statistical t-tests were then used to compare the test scores between the schools and the non-parametric Mann-Whitney U tests were performed as a double check.

A statistically significant difference was found between school 1- control and school 2 pre- test scores. The T1(school 1) (M=4.0, SE=0.46) to T1(school 2) (M=2.9, SE=0.27) was

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considered to be statistically significant, (t(71)=2.17, p<0.05 (p=0.03), r=0.25), although the effect size was very small.

Mann-Whitney U test

The Mann-Whitney U test supported the un-paired t-test, showing a small effect size (Median S1 = 3; Median S2 = 3; U=408.5; P=0.057; r=0.22). However, the probability was on the 95% significance level.

Power

The observed power was 56.8%

Comment

The mean scores of the two schools pre-test would suggest that there was a small difference between the schools. This was reflected in the non-parametric independent statistical test. However, since the effect size was small and the 95% probability value in the Mann-Whitney U test was greater than 0.05, this suggests that there may not be a difference. Since the power was low (56.8%) a definitive answer could not be given. Therefore, there may or may not have been a small difference pre-test between the schools. However, the importance of this was low since both schools reached the same mean score on the immediate post-test. Therefore school 2 (test) either made a more significant improvement to the immediate post-test or the same improvement as school 1.

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Figure 17. Pre-test, immediate post-test and 1 month post-test means for school 1 and school 2

T2 Comparison

Un-paired t-test

An unpaired t-test was then performed on both schools’ immediate post-test results.

The T2(school1) (M=8.43, SE=0.51) to T2(school 2) (M=8.5, SE=0.38) was not considered to be statistically significant (t(71)=0.48, p>0.05 (p=0.62), r=0.06). Therefore, both schools attained the same knowledge gain in the immediate post- tests.

Mann-Whitney U test

The Mann-Whitney U test supported the results of the un-paired t-test that there was not a statistically significant difference between the immediate post test scores for both schools (Median S1 = 8; Median S2 = 9; U=515.5; P=0.559; r=0.06).

Power

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Comment

The effect size was extremely low, and the 95% probability value was greater than 0.05. This, together with the mean scores of 8.5 and 8.43, suggested that there was no

difference between the schools on the immediate post-test. However, since the power was low (50.7%) a definitive conclusion could not be derived, but relative to the other data it seemed reasonable to conclude that there was no difference.

Un-paired t-test

An unpaired t-test was then performed on the one month post-tests for both schools. The T3(school1) (M=5.69, SE=0.44) to T3(school 2) (M=7.6, SE=0.35) was considered to be statistically highly significant (t(69)=3.22, p<0.05 (p=0.001), r=0.43). This showed that the large gain by both schools was retained statistically significantly only by school 2. This was also evident on the means graph for all test results (figure 17) and on the trend graphs (figures 14 and 15).

Mann-Whitney U test

The Mann-Whitney U test supported the un-paired t-test results showing statistically that the large gain by both schools was retained only by school 2 (Median S1 = 6; Median S2 = 8; U=293.5; P<0.05 (p=0.002); r=0.372).

Power

The observed power was 66.8%

Comment

The effect size was large and the 95% probability value was less than 0.05 which suggests that there was a significant difference between the 1 month post-test results. Moreover,

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since there was a significant difference between the median scores for the 1 month post- tests, this supported the view that there was a highly significant difference. However, the power was low (66.8%) and so doubt remains. Nevertheless, all other data indicates a highly significant difference.

Can a more productive learning method be developed which will significantly increase the knowledge uptake by primary school children in a chemical safety intervention?

School 2 (test) appeared to have a greater knowledge gain than school 1(control) from pre-test to immediate post-test: 34.8% for school 1 and 43.3% for school 2. However, school 2 started at a lower level in the pre-test and so this may have been due to

regression to the mean. Therefore, the result was unclear. The results suggested that the null hypothesis should be rejected, but further studies would be required utilising a greater sample size in order to give a definitive answer. What was clear from the results was that there was a highly significant knowledge gain for both schools pre-test to immediate post- test. For both schools the effect size was large and the power was over 80% (88.9% for school 1and 97% for school 2).

If there has been an increase in knowledge uptake has this been retained over a 1 month period?

For school 1 (control) from pre-test to 1 month post-test there was a significant improvement in knowledge gain which was 13.7%. However, the effect size was only medium, and the fall-back over the month was 21.1%. The power, however, was below the standard 80%, though only just so at 76.1%. For School 2 (test) from pre-test to 1 month post-test a 36% improvement was retained, and the fall-back after 1 month was only 7.3%. The effect size was large, and the power was over 80% at 96.7%.

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The results appeared unequivocally to support the rejection of the null hypothesis. This study seemed to demonstrate clearly that the teaching to learning styles / active learning methods produced a far larger retention of the knowledge gained. However, there is one caveat. The un-paired test between the schools for the 1 month post-test, whilst giving a large effect size, had only 66.8% power which was below the standard 80% power. All other indicators agreed that the null hypothesis should be rejected, but this result should be treated with some caution. A greater sample size in future studies would provide more certain results.