Hi guys! i’ve tried to perform statistical analysis from ROI geometry at merapi volcano. the results shown like the pic above. what does the **Max Error**, **ENL** and **Coef varian**means? how it is being calculated?

Thanks

Hi guys! i’ve tried to perform statistical analysis from ROI geometry at merapi volcano. the results shown like the pic above. what does the **Max Error**, **ENL** and **Coef varian**means? how it is being calculated?

Thanks

the coefficient of variation is the standard deviation of all values divided by the average (mean) value.

Thanks for the answer. how about the **Max Error** means? how is it being estimated?

I’m sorry mr. Braun, i still have no clue about **Max Error** means. could you please answer my question? thanks

I just don’t know it, sorry. Maybe someone else can comment.

I think I can shed some light on these values:

**Coef Variation:**

This is differently computed depending on the unit of the data:

```
if (unit != null && unit.contains("intensity")) {
final double m = valueSum / sampleCount;
final double m2 = sqrSum / sampleCount;
cv = Math.sqrt(m2 - m*m) / m;
} else {
final double m4 = power4Sum / sampleCount;
final double m2 = sqrSum / sampleCount;
cv = Math.sqrt(m4 - m2*m2) / m2;
}
```

The code can be found here: snap-engine/SummaryStxOp.java

Background information: Coefficient of variation - Wikipedia

**ENL:**

```
if (unit != null && unit.contains("intensity")) {
final double m = valueSum / sampleCount;
final double m2 = sqrSum / sampleCount;
final double mm = m*m;
enl = mm / (m2 - mm);
} else {
final double m4 = power4Sum / sampleCount;
final double m2 = sqrSum / sampleCount;
final double m2m2 = m2*m2;
enl = m2m2 / (m4 - m2m2);
}
```

The code can be found here: snap-engine/SummaryStxOp.java

Background information: Estimation of the Equivalent Number of Looks in Polarimetric Synthetic Aperture Radar Imagery | IEEE Journals & Magazine | IEEE Xplore

**Max error:**

This is actually the bin size.

The code can be found here: snap-desktop/StatisticsPanel.java

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