dftolss -- Sample size calculation for distribution-free tolerance intervals


dftolss , [conf(#) beta(#) r(#)]

options Description ------------------------------------------------------------------------- conf(#) set confidence level of the tolerance interval; default is conf(95) beta(#) set percentage of the population covered by the tolerance interval; default is beta(95) r(#) set the number of blocks removed; default is r(2) -------------------------------------------------------------------------


dftolss computes the smallest sample size for the tolerance intervals obtained removing r(#) blocks to contain, at confidence level conf(#)%, at least a percentage beta(#)% of the sampled population. See also dftol.


dftolss requires that the Stata module -moremata- (Jann, 2005) be installed.


conf(#) specifies the confidence level of the tolerance interval as a percentage. The default is conf(95), meaning a 95% confidence level.

beta(#) specifies the percentage of the sampled population to be contained in the tolerance interval. The default is beta(95), meaning a percentage equal to 95%.

r(#) specifies the number of blocks removed. The default is r(2), which, according to the definition of block (see Murphy, 1948) means that the endpoints of the tolerance interval would be the smallest and largest observations of the sample. Note that for r(1), i.e. when only one block is removed, the interval reduces to a one-sided lower (alternatively, upper) tolerance bound.


. dftolss . dftolss, c(90) b(90) . dftolss, c(99) b(99) r(4)

Saved results

dftolss saves the following in r():


r(n) sample size)


Ignacio López de Ullibarri Department of Mathematics University of A Coruña, Spain E-mail: ilu@udc.es


Jann B (2005), moremata: Stata module (Mata) to provide various functions, available from http://ideas.repec.org/c/boc/bocode/s455001.html

Murphy RB (1948), Non-parametric tolerance limits, Annals of Mathematical