Benutzerhandbuch Menü

# Chi2 test

When checking the normality of a distribution our first intuition would be to draw a histogram of the distribution of the observed variables to see how closely it resembles a normalized Gaussian curve.
This is the exact principle behind the Chi2 test that adds to this intuition a small dose of statistical calculations. The principle is as follows:
For each bar of the histogram we can calculate:
• Ni: The number of parts actually observed (here 10)
• Npi: The number of parts theoretically observed if it were a normal distribution (here 9.2)
• represents the “number of badly arranged parts”
We then calculate ,and find that D follows a distribution law due to the n-2 degrees of freedom (N being the number of classes). Consequently, we can calculate the probability of getting such a value
For example; for a histogram composed of 7 classes, if we calculated one d at 11.07 then we calculate that there are 5% that obtain this value, or more if the distribution law for the parts is actually normal.
The result of the test would therefore be 5% and we generally conclude in the following way:
• If X < 5%: the variables distribution law is not considered to follow a normal distribution
• If X >= 5%: the normality hypothesis is accepted and we consider that this distribution law follows a normal distribution.

Versuch

0

30 Tage

Testen Sie es kostenlos

APC

SPC

Kontrolle

Analyse

30 Tage

Alle Funktionen von Ellistat

1 Benutzer

Technische Unterstützung und Wartung inbegriffen

Student

0

1 Jahr

Zur Kasse

Analyse

1 Jahr

Alle Funktionen von Ellistat

1 Benutzer

Lizenz für Studenten, die über einen gültigen Studentenausweis verfügen

Technische Unterstützung und Wartung inbegriffen

Standard

49

pro Benutzer pro Monat

Zur Kasse

Analyse

Lizenz wird alle zwei Monate erneuert

Alle Funktionen von Ellistat

Unbegrenzter Benutzer

Technische Unterstützung und Wartung inbegriffen