# Find parameter distribution how i know any initial value i must put?

Using your data and probability distribution from a previous question of yours, the following works fine on Mathematica 12.2 (Windows 10):

``````dist = ProbabilityDistribution({"CDF", Divide(1 - Exp(λ (1 - Exp((1 - Exp(-(x/α)^γ))^β))),
1 - Exp(λ - λ Exp(1)))}, {x, 0, ∞}, Assumptions -> {λ > 0, β > 0, α > 0, γ > 0})

data = {70, 90, 96, 97, 99, 103, 104, 104, 105, 107, 108, 108, 108,
109, 109, 112, 112, 113, 114, 114, 114, 116, 119, 120, 120, 120,
121, 121, 123, 124, 124, 124, 124, 124, 128, 128, 129, 129, 130,
130, 130, 131, 131, 131, 131, 131, 132, 132, 132, 133, 134, 134,
134, 134, 136, 136, 137, 138, 138, 138, 139, 139, 141, 141, 142,
142, 142, 142, 142, 142, 142, 142, 144, 144, 145, 146, 148, 148,
149, 151, 151, 152, 155, 156, 155, 156, 157, 157, 157, 157, 158,
159, 162, 163, 163, 164, 166, 166, 168, 170, 174, 201, 212};

mle = FindDistributionParameters(data, dist, {{λ, 47}, {β, 1.5}, {α, 20}, {γ, -4}})
(* {λ -> 2.91285, β -> 3.45368, α -> 133.646, γ -> 3.37814} *)

Show(Histogram(data, "FreedmanDiaconis", "PDF"),
Plot(PDF(dist /. mle, x), {x, Min(data), Max(data)}))
``````

So you might want to try starting values closer to the maximum likelihood estimates or increase the maximum number of iterations (say, `MaxIterations->5000`).