Statistical tables

Beta Distribution Table

Table of the Beta distribution Be(α, β): cumulative distribution P(X ≤ x), density f(x) and quantiles for different α and β parameters. The support is x ∈ (0, 1). Click a cell to read the value.

How to read the table: each cell shows P(X ≤ x) for the selected parameters α and β. The row gives the first decimal digit of x; the column adds the second (×0.01). The range is x ∈ [0.00, 0.99].
Click a cell to read the value.

P(X ≤ x) for x from 0.00 to 0.99

x.00.01.02.03.04.05.06.07.08.09
0.00.00030.00120.00260.00470.00730.01040.01400.01820.0228
0.10.02800.03360.03970.04630.05330.06080.06860.07690.08550.0946
0.20.10400.11380.12390.13440.14520.15630.16760.17930.19130.2035
0.30.21600.22870.24170.25480.26820.28180.29550.30940.32350.3377
0.40.35200.36650.38100.39570.41040.42530.44010.45510.47000.4850
0.50.50000.51500.53000.54490.55990.57470.58960.60430.61900.6335
0.60.64800.66230.67650.69060.70450.71820.73180.74520.75830.7713
0.70.78400.79650.80870.82070.83240.84380.85480.86560.87610.8862
0.80.89600.90540.91450.92310.93140.93930.94670.95370.96030.9664
0.90.97200.97720.98180.98600.98960.99280.99530.99740.99880.9997
How to read the table: each cell shows f(x) = x^(α−1) · (1−x)^(β−1) / B(α,β). For α < 1 or β < 1 the density may diverge at the endpoints (very large values are shown as "∞").
Click a cell to read the value.

f(x) for x from 0.00 to 0.99

x.00.01.02.03.04.05.06.07.08.09
0.00.05940.11760.17460.23040.28500.33840.39060.44160.4914
0.10.54000.58740.63360.67860.72240.76500.80640.84660.88560.9234
0.20.96000.99541.02961.06261.09441.12501.15441.18261.20961.2354
0.31.26001.28341.30561.32661.34641.36501.38241.39861.41361.4274
0.41.44001.45141.46161.47061.47841.48501.49041.49461.49761.4994
0.51.50001.49941.49761.49461.49041.48501.47841.47061.46161.4514
0.61.44001.42741.41361.39861.38241.36501.34641.32661.30561.2834
0.71.26001.23541.20961.18261.15441.12501.09441.06261.02960.9954
0.80.96000.92340.88560.84660.80640.76500.72240.67860.63360.5874
0.90.54000.49140.44160.39060.33840.28500.23040.17460.11760.0594
How to read the table: each cell shows the quantile x such that P(X ≤ x) = p. Rows: different values of α. Columns: cumulative probabilities p. Select β with the selector.
Click a cell to read the value.

Quantiles Be⁻¹(p; α, β) — P(X ≤ x) = p

α \ p0.010.0250.050.10.250.50.750.90.950.9750.99
0.50.00010.00060.00250.01000.06250.25000.56250.81000.90250.95060.9801
10.01000.02500.05000.10000.25000.50000.75000.90000.95000.97500.9900
1.50.04640.08550.13570.21540.39690.63000.82550.93220.96640.98330.9933
20.10000.15810.22360.31620.50000.70710.86600.94870.97470.98740.9950
2.50.15850.22870.30170.39810.57430.75790.89130.95870.97970.98990.9960
30.21540.29240.36840.46420.63000.79370.90860.96550.98300.99160.9967
40.31620.39760.47290.56230.70710.84090.93060.97400.98730.99370.9975
50.39810.47820.54930.63100.75790.87060.94410.97910.98980.99490.9980
70.51790.59040.65180.71970.82030.90570.95970.98510.99270.99640.9986
100.63100.69150.74110.79430.87060.93300.97160.98950.99490.99750.9990

How to use these tables

Beta Distribution

The Beta distribution Be(α, β) has support on [0, 1] and is very flexible for modeling proportions and probabilities. Its density function is:

\( f(x;\alpha,\beta) = \dfrac{x^{\alpha-1}(1-x)^{\beta-1}}{B(\alpha,\beta)}, \quad x \in (0,1) \)

where B(α, β) = Γ(α)Γ(β)/Γ(α+β) is the beta function. The mean is μ = α/(α+β) and the variance σ² = αβ / [(α+β)²(α+β+1)].

Shapes of the distribution

  • α = β = 1: Uniform(0,1) distribution.
  • α = β > 1: unimodal and symmetric around 0.5.
  • α > β: left-skewed (mean > 0.5).
  • α < β: right-skewed (mean < 0.5).
  • α < 1 or β < 1: U-shaped (bimodal at the endpoints).

Relationship with F and t

If F ~ F(2α, 2β) then X = αF/(β + αF) ~ Be(α, β). The regularized incomplete beta function is also the CDF of the F distribution and of Student's t distribution.

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