
Re: Help with probability&stat problem
Posted:
Jun 13, 2007 11:53 AM


> Bob wrote: > > > *** I'll leave it to others to decide whether 0.9717 > and 0.9786 are more than slightly different, *** > > My response > > You SHOULD NOT leave to others but to THINK ABOUT. > The way I posted is the *one* when the signal o the > error I unimportant. > You made an error of analysis: it is not throughout > the Z values that the errors must be chosen but by > the associated tail probabilities, evidently. > ********************* > > Bob: > > *** But i find this curious: are you really saying > that one must use the Normal approximation with a > continuity correction, rather than the exact binomial > calculation? If so, why? And why can't this be > disputed? *** > > My response > > OF COURSE NOT: I didn?t and I?ll never say such > nonsense. > > The reason by which the normal approximation is used > is that is immediate. On contrary the exact way needs > computer programming. If available, do not hesitate: > use it. If not, the only *decent* way is to use the > continuity correction. > > IT`S SIMPLE, ISN`T IT? > ********************** > > Licas
For the binomial distribution calculations in Excel, you don't need to know BASIC programming. You just use the BINODIST function. It takes about 20 seconds to type in the arguments.
The normal distribution, based on NORMSDIST, takes longer because you have to calculate the argument (xpN+0.5)/sqrt(p*(1p)*N). What you achieve with the added time consumed is an inaccurate approximation of an assymmetric distribution by a symmetric distribution.
Jack

