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The bottom perimeter line of the yellow box indicates the
lower quartile
value. This line shows the
value below which 25% of the accident rates lie when the rates are arranged in order from smallest to
largest. In this case the value is 0.005 per 10,000 movements.
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In conjunction with the minimum value, this indicates that 25% of States had an accident rate between
0.000 and 0.005 accidents per 10,000 movements.
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In conjunction with the median value, this indicates that a further 25% of States had an accident rate
between 0.005 and 0.035 accidents per 10,000 movements;
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The upper perimeter line of the yellow box indicates the positioning of the
upper quartile.
This line
shows the value above which 25% of the accident rates lie when the figures are arranged in order from
smallest to largest. In this case, the value is 0.035 per 10,000 movements;
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In conjunction with the median value this indicates that 25% of States had an accident rate between
0.035 and 0.055 accidents per 10,000 movements;
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Two states had accident rates that were identified as outliers.
Outliers
are observations that are nu‑
merically distant from the rest of the data and are identified using a formula. The two States concerned
both regulated AOC holders who each experienced a single accident and performed a relatively low
number of movements; 87,639 and 135,634 respectively by state. These flight movement numbers
were the eighth and eleventh smallest numbers of movements among the 32 States;
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Many of the higher accident rates were associated with States whose AOC holders conducted a small
proportion of the overall movements and experienced either one or two accidents;
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Where movements are considered as the measurement of size, the State that regulated the largest
share of the aviation industry has the eleventh lowest accident rate and the AOC holders it regulates
have experienced 21 accidents;
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The differences between accident rates of individual States are not statistically significant.
Using this information
The purpose of providing these statistics is to allow States and AOC holders to compare their accident rates with
the statistics provided here at a European Level.
For example, where AOC holders in a given State have conducted 600,000 movements over the last 4 years and
experienced 3 accidents, their accident rate per 10,000 movements is 0.050. (Calculation is 3/600,000*10,000).
This indicates that the accident rate for that State, or AOC holder, lies between the median and upper quartile.
Similarly, that State’s accident rate is lower than 25% of all accident rates and higher than 50% of all accident
rates.