# Metrics (Statistical Collector / Performance data)

### Table of Contents

## About

This page is about metrics in Monitoring.

A monitoring/performance metrics is a:

- timestamped
- numerical value

## Other name

Monitoring Metrics are also known as:

- Statistical Collector
- Perfcounter (generally on Windows)
- Performance metrics
- Performance data

They are known as statistical data collectors because they gather data and compute statistics. They are used to collect, evaluate and report results, e.g.

- mean residence times of customers
- or the average utilisation of a server.

## Aggregated metrics / Statistics

An aggregated metrics is

- calculated from time serie data.
- a statistic(s) (See also the page Counter - Statistics (for Engineers on operational data))

They are event metrics.

For the business related view of metrics, see Dimensional Data Modeling - Metrics - Key Performance indicators (KPI)

## Type

- Timer, a Timer measures both the count of timed events and the total time of all events timed.
- Counter is used to record occurrences of events like the number of customer arrivals. Representing a counter without rate aggregation over some time window is rarely useful, as the representation is a function of both the rapidity with which the counter is incremented and the longevity of the service.
- Gauge, - a single metric (gauge values are not rates)
- histogram - An histogram ranks the measured values into predefined classes.
- Regressions: A Regression perform a regressional analysis of two different collected value series (x and y). It reports the number of observations, mean (for x and y), regression and correlation coefficients, standard deviations and interception.

Time serie:

- Tallies. A tally record the mean and standard deviation of a (time) series of values. Example: Computing the average time customers spent on a system
- Accumulates: An Accumulate record the mean and standard deviation of a time series of values against different time interval. Example: System load

See also: Prometheus Metrics Type

## Implementation

- Statistical Data Collectors (desmoj.core.statistic package)