# Ticket #200 (new task)

## Magnitude quality estimator is needed for localmag and TYPE_MAGNITUDE

Reported by: | paulf | Owned by: | matteo |
---|---|---|---|

Priority: | minor | Milestone: | All Platforms |

Component: | localmag | Version: | 7.6 |

Keywords: | magnitude quality | Cc: |

### Description

Fraco Mele in ticket #176 indicated that a quality estimator to judge how good the magnitude is would be a useful feature or localmag since the ML magnitudes can often be skewed when few stations are usable.

I am just continuing the discussion of this in this new ticket since the prior ticket was a localmag station filter algorithm implementation.

I believe ticket #176 should be closed now if all discussions there in were implemented...did anyone think about doing the Md distance filter? That is, use a the Md in the HYP2000ARC message as a distance estimator for how far to include stations in the ML computation.

## Change History

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in wrML (lm_main.c @ 4724)

the following are defined and never used:

Also, the number of used channels is computed:

As a first attempt to define a magnitude quality in the range [0, 1], I would suggest :

where MI.mag is the magnitude and MI.nchannels is the number of channels that contributed to the ML computation.

MLQpar1 should be a parameter proportional to the density of the stations. For instance: for the Italian network MLQpar1 could be 10.

Other ML-quality estimators with values in the range [0, 1] could be easily combined to this one by multiplication.

We could also take into account for standard deviation, minimum station distance or (maximum - minimum) distance range, among the stations used in the ML computation.

Other suggestions would be greatly appreciated :-)

ciao,

franco