GARP協會的官方版本,還有其他兩個考綱的教材,也出現「經驗法則」(rule of thumb)用語:
其一:
QA-2.6解讀統計分配的偏度與峰度,並解讀「共偏度」(coskewness)與「共峰度」(cokurtosis) 。
在GARP協會的官方版本教材p.23頁出現下列一段文字:
For many symmetrical continuous distributions, the mean, median, and mode all have the same value. Many continuous distributions with negative skew have a mean that is less than the median, which is less than the mode. For example, it might be that a certain derivative is just as likely to produce positive returns as it is to produce negative returns (the median is zero), but there are more big negative returns than big positive returns (the distribution is skewed), so the mean is less than zero. As a risk manager, understanding the impact of skew on the mean relative to the median and mode can be useful. Be careful, though, as this rule of thumb does not always work. Many practitioners mistakenly believe that this rule of thumb is in fact always true. It is not, and it is very easy to produce a distribution that violates this rule.
這段文字也只出現在GARP協會的官方版本教材。SchweserNotes與GARP協會的Practice Exams及Handbook都找不到這一段文字。
這一段文字,主要是說明:
許多對稱的連續分配,有相同的平均數、中位數及眾數。許多負偏的連續分配,平均數小於中位數,中位數也小於眾數。例如某些衍生性金融商品,產生正數的報酬率與產生負數的報酬率有相同的機率 (中位數是零)。但是有一個比大的正數報酬率還要大的負數報酬率(該分配為偏態),因此該平均數小於零。身為一位風控長,了解偏態對平均數相對於中位數與眾數的影響很有用。但是,要小心,因為這個經驗法則,不一定成立。許多實務界人士誤以為這個經驗法則一定成立。實際上並不是,因為很容易產生違背這個經驗法則的分配。
其二:
考綱FMP-6.3定義「基差」(basis)與「基差風險」(basis risk)的各種來源,並解釋以期貨避險時的基差風險。
在GARP協會的官方版本教材p.91頁出現下列一段文字:
In general, basis risk increases as the time difference between the hedge expiration and the delivery month increases. A good rule of thumb is therefore to choose a delivery month that is as close as possible to, but later than, the expiration of the hedge.
這段文字也只出現在GARP協會的官方版本教材。SchweserNotes與GARP協會的Practice Exams及Handbook都找不到這一段文字。
這一段文字,主要是說明:
一般而言,隨著避險到期日與交割月份的時間差越大,基差風險也越大。因此,根據經驗法則,盡可能選擇一個接近避險到期日,但是又超過避險到期日的交割月份。