# Which normalization method for different units (zero, negative, etc.)

Commonly, normalization of ratings seems to mean adjusting values measured on different scales to a notionally common scale.

I have different metrics that measure different performance aspects of a server. I want to aggregate these values. The problem is:

• The values are on different scale types (interval and ratio scale)

• The values have different minimum and maximum values

Most of them are between $$0.0$$ and $$1.0$$, where $$0$$ means complete absence of the measured attribute and $$1$$ means the attribute is maximized to the best characteristic it can gain.

• One of the ratio scale values can be $$[0, \infty]$$. Theoretically, speaking, practically something around $$500$$. More is here better $$0$$ is absence, too.

• The interval scale can be negative, positive and zero. Zero does not mean, absence. The less, the better. The more, the worse.

How do I approach this? I need to aggregate the results and feel a bit lost. I see two options here.

1. Use a normalization, but which one? Ideally I would all map to $$[0,1]$$ so I can present them as percentage, although that would be unprecise for the one ratio and the one interval.

I know min-max scaling (feature scaling?), but is that appropriate? What about z-score? With z-score however, it seems I will land again on a negative-positive scale.

2. Use a tendency to aggregate, arithmetic mean (needs normalization), geometric mean (false semantic on zero results), adjusted geometric mean, etc.

How should I approach this, can someone advise me?