Scalar which contains the required efficiency (of location
or scale estimator).

Generally eff=0.85, 0.9 or 0.95

**
Data Types: **`single|double`

e.g. in regression v=1

**
Data Types: **`single|double|int32|int64`

The asymptotic rejection probability of an estimator is
defined as the probability in large sample under a
reference distribution that a Malanobis distance excees
$c_0$, where $c_0=inf \{ u_0 | w(u)=0, \forall u>u_0 \}$.

$w(u)$ is the weight function (defined in RKwei.m). In
other words, given $c_0=sup(\rho(u))$,if an estimator is normed
to the normal distribution ARP is $1-F_{\chi^2_v}(c_0^2)$.

The default value of ARP is 0.05.

**Example: **```
0.04
```

**
Data Types: **`double`