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Normal tail mean and density practice

These original questions connect the standard-normal first moment to a selected-tail average.

Use the original 95% model

Mean loss is zero and dispersion ten. Standard normal z is approximately 1.644854, density at z approximately 0.1031356404 and upper-tail probability 0.05.

Keep the three objects distinct

The density equality follows from the normal first-moment integral. A density height is not itself a point probability or an already normalised tail mean.

Try the questions

What is the 95% standard-normal tail-mean multiplier?

  • A.

    0.1031356404 approximately

  • B.

    2.0627128075 approximately

  • C.

    1.644853627 approximately

Answer and explanation

Answer: B

The selected tail probability supplies the denominator.

A

This is the unnormalised first moment.

B

Divide the first moment by 0.05.

C

This is the quantile threshold.

What is probability at exactly zero under a positive-dispersion continuous normal law?

  • A.

    0

  • B.

    0.398942 approximately

  • C.

    50%

Answer and explanation

Answer: A

Interval area, not curve height, gives probability.

A

A single point has zero probability under this continuous law.

B

That is the standard density height at zero.

C

That confuses a point with a half-line event.

With mean loss 7 and dispersion zero, how should the tool treat the record?

  • A.

    Constant loss, VaR and ES both 7, no density figure

  • B.

    Divide the density by zero

  • C.

    Set both summaries to zero

Answer and explanation

Answer: A

The constant loss amount need not be zero.

A

This is the degenerate constant limit.

B

The positive-scale expression is undefined.

C

That discards the entered constant loss.

Further references