chi-square distribution

E596523

The chi-square distribution is a continuous probability distribution commonly used in statistics to model the sum of squared standard normal variables and to conduct hypothesis tests such as goodness-of-fit and tests of independence.

All labels observed (4)

Label Occurrences
Pearson's chi-squared test 1
chi-square distribution canonical 1
chi-squared distribution 1

How this entity was disambiguated

Statements (47)

Predicate Object
instanceOf probability distribution ⓘ
right-skewed distribution ⓘ
assumes independent observations in contingency tables ⓘ
sufficiently large expected cell counts for chi-square approximation ⓘ
belongsTo family of Pearson distributions ⓘ
cdf regularized gamma function of x/2 and k/2 ⓘ
characteristicFunction φ(t) = (1 - 2it)^{-k/2} ⓘ
cumulativeShape increasing and concave for small x ⓘ
definedOn nonnegative real numbers ⓘ
hasProperty approaches normal distribution as degrees of freedom increase ⓘ
nonnegative random variable ⓘ
right-skewness decreases as degrees of freedom increase ⓘ
hasScaleParameter 2 in gamma representation ⓘ
hasShapeParameter k/2 in gamma representation ⓘ
introducedBy Karl Pearson ⓘ
isSpecialCaseOf gamma distribution ⓘ
kurtosisExcess 12/k ⓘ
mean k (degrees of freedom) ⓘ
mode k - 2 for k ≥ 2 ⓘ
momentGeneratingFunction M(t) = (1 - 2t)^{-k/2} for t < 1/2 ⓘ
origin distribution of quadratic forms in normal variables ⓘ
sum of squares of independent standard normal variables ⓘ
parameter degrees of freedom ⓘ
pdf f(x;k) = 1/(2^{k/2} Γ(k/2)) x^{k/2-1} e^{-x/2} for x>0 ⓘ
relatedTo F-distribution ⓘ
Student's t-distribution ⓘ
gamma distribution ⓘ
standard normal distribution ⓘ
skewness √(8/k) ⓘ
specialCase exponential distribution when k = 2 ⓘ
support [0, ∞) ⓘ
symbol χ² ⓘ
tailBehavior heavy right tail for small degrees of freedom ⓘ
usedFor confidence interval for variance ⓘ
goodness-of-fit test ⓘ
test of homogeneity ⓘ
test of independence ⓘ
variance test ⓘ
usedIn analysis of variance ⓘ
categorical data analysis ⓘ
contingency table analysis ⓘ
hypothesis testing ⓘ
likelihood ratio tests ⓘ
maximum likelihood estimation theory ⓘ
usedWith Pearson's chi-square test ⓘ
likelihood ratio chi-square test ⓘ
variance 2k (degrees of freedom) ⓘ

How these facts were elicited

Referenced by (4)

Full triples — surface form annotated when it differs from this entity's canonical label.

Gamma function → appearsIn → chi-square distribution ⓘ
Karl Pearson → notableWork → chi-squared test ⓘ
linked to: chi-square distribution
F-distribution → relatedDistribution → chi-squared distribution ⓘ
linked to: chi-square distribution
Fisher's exact test → alternativeTo → Pearson's chi-squared test ⓘ
linked to: chi-square distribution