*5.1. Longitudinal Study*

Table 3 shows the results for the various correlation and regression tests. The variables tested included:



**Table 3.** Correlation and regression test results for the various longitudinal factors.

All of the tests were statistically significant. The results for the proportions match the respective raw count results, which is to be expected. However, the proportion results enable the β values to be directly compared, since they are relative counts. We note that maintenance accidents appear to have reduced over time 2.5 times faster than the rate of reduction in all ICAO official accidents. The statistical significance of this is supported by the results for the model given by (3). Figure 11 shows the annual accident counts for the accidents with maintenance contributions and all of the ICAO official accidents.

**Figure 11.** The trends over time for accidents with maintenance contributions (secondary axis, purple line with large dashes) and all ICAO official accident (blue line with small dashes).
