User's Guide Menu

User Guide

Abnormal value test

When analyzing a data set it can happen that we are confronted with values that do not seem to be a part of the normal data distribution. We call these abnormal value points and, as usual, you should not trust your intuition in detecting if a value is abnormal or not. There are tests that will show this.
From a statistical point of view, an abnormal value is a value that does not belong to the normal data distribution. It can come from:
  • A measurement error or copying error (forgetting a decimal)
  • A special reason such as a part that was not washed prior to being measured.
The entirety of statistical calculations using normal distribution properties (statistical tests, capability calculations, off-tolerance % calculations) is very sensitive to the presence of abnormal values. It is therefore important to understand their origin and to eliminate them before using these calculations. We may be able to use the non-parametric statistical tests, which are much less sensitive to abnormal values.
Deux tests sont principalement utilisés :
  • Dixon test: very applicable when the amount of data is low (<30)
  • Grubb test: can be used in all cases.

A complete solution for Industry 4.0

8 Statistical Modules

trial

Trial

€ 0

1 month

Try it for free

APC

SPC

Control

Analysis

check

1 month

check

All feature's of Ellistat's Analysis Module.

check

1 user

Technical support and updates included.

student

Student

€ 0

1 year

Checkout

Analysis

check

1 year

check

All feature's of Ellistat's Analysis Module.

check

1 user

check

Dedicated student licence upon presenting a valud student card.

Technical support and updates included.

standard

Standard

€ 49

per user per month

Checkout

Analysis

check

Automatic monthly renewal

check

All feature's of Ellistat's Analysis Module.

check

Unlimited users.

check

Technical support and updates included.