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Non-central t distribution
Computes a table of probabilities.
2024.Jul.03 18:24:13
n Sample size (degrees of freedom, idf = n − 1). •
AQL or δ   AQL = %  or δ = Choose: AQL or non-centrality δ. •
prob or t   P = %  or  t = Choose: prob from t (direct) or t from prob (inverse). •
tmin, tmax Table t min. and max., and n. of rows. •
Show values ? Shows the coordinates of the graph. •

Computes a table of probabilites of the non-central (noncentral) t distribution ('nct'), with its two (given) parameters: 'idf', degrees of freedom; and δ, noncentrality parameter.

As the 'nct' is important in Quality Control, the table follows typical AQL values (Renard-type series ...0.65 %, 1 %, 2.5 %, 4 %, 6.5%...). Other particular values can be supplied: (a) either AQL or δ; and (b) either probability (inverse 'nct') or t (direct 'nct'). An Excel file.xlsm (by J. Frickmann) is supplied for the direct 'nct', for comparison. (The xlsm files may pose security threats.)

If it is tmin = tmax, then these are computed: tmin = Tnc(1%, max(AQL)) and "max 99% min".

Plots the cumulative distribution ('cdf') vs. t for various AQL values.

References: Plate: Noncentralt

• ASQ Glossary, letter A (search 'AQL'), 'acceptance quality limit' in Quality Control (American Society for Quality).

• Wikipedia: Noncentral t-distribution.

• Keisan Online Calculator: Noncentral t-distribution (Casio Computer Co. Ltd.).

Burkardt, John, ASA005, CDF of Noncentral T Distribution.

• Resnikoff & Lieberman; Tables of the non-central t-distribution, Technical Report No. 32, April 1, 1957 (=.pdf), Stanford: Dept. of Statistics.

• 1870-02-12: Carslaw, Horatio Scott (1954-11-11).

 
 
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Created: 2017-02-12 — Last modified: 2017-02-17