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PE & CI's for μ & σ, optimized
Computes point estimate & CI's from unequal size samples' sums.
2024.Nov.25 07:49:35
Sizes Sample sizes (for simulation). •
μ, σ Gaussian parameters for the samples. •
Confidence level % Level for the confidence intervals. •
Trials, points, seed Monte Carlo trials, histogram points, seed. •
Candidate "equal" (> 0 overrides previous.) Equal size equival.: aver. | min | max (in table) | other. •
Scale factor Factor (1.st iff 'Verify'; both (bracket) iff 'Optimize'). •
x-limits for plots x axis limits for plots (±i for infinity).
Show values Show the graph coordinates.

Computes (analytically) point estimates (PE) and (by Monte Carlo) confidence intervals (CI) for μ and σ (Gaussian parameters) from sample sums alone. Here, the sums are simulated from given μ and σ, thus expected to be recovered.

As a conjecture, the average sample size leads to: a Student's t with n − 1 (nearest integer) degrees of freedom; and a chi-square with T − 1 df, and, as a proposal, an adjustable scale factor. This scale factor is optimized so that the simulated and proposed curves "coincide".

Simulates N (trials) sets of T samples, each with (generally) unequal nt (t = 1..T) elements (as in the Sizes above, T = 4), in order to compute “exact” confidence intervals. Many (analytical) point estimates are computed, and their (simulated) behavior leads to the confidence intervals.

In industry, the sample sizes are usually unequal (different customers' orders). Two questions remain. The candidate n seems to be the arithmetic mean of the n 's. For the default data, the average n (25) makes the curves for the mean coincide. For the variance, a rule for the scale was not found. (For the basis problem, scale is 0.0135.)

Warning: large data sets may lead to excede a typical (Web) time limit (~2 min) with error message as '502 Bad Gateway'. Speed: ~400 million Gaussians/min.

Draws plots of: the estimated value of μ; and the estimated value of σ².

References: Plate: BagsPECIsimOpt

• 1.3.6.4. Location and Scale Parameters ("formulas for") (NIST/SEMATECH e-Handbook…).

• Keisan Online Calculator: Chi-square distribution Calculator (Casio Computer Co., Ltd.).

• 1883-06-05: Keynes, John Maynard († 1946-04-21, 62 yrs.).

 
 
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Created: 2022-06-05 — Last modified: 2022-06-05