sum(toss == 1) /length(toss) # assuming heads == 1 On 10/16/07, azzza <[EMAIL PROTECTED]> wrote: > > > THANKYOU guyz! yes, Jim's code was right (it was similar to someone > elses)....I somehow missed his reply! > Yes, that was exactly what i was looking for. lastly, how do i find the > frequency of heads perhaps? > > > > Marc Schwartz wrote: > > > > On Tue, 2007-10-16 at 11:53 -0700, azzza wrote: > >> > >> > >> ok, so suppose a coin is tossed 1000 times. Each time head occurs, we win > >> a > >> dollar, otherwise we lose a dollar. Let S(n) be our accumulated winnings > >> after n tosses. For instance, if the sequence HHHTT occurs in the first > >> five > >> tosses, then S(5) = $1.00 wheras if the sequence HTTTT occurs, S(5) =-$3. > >> So > >> now, we want to see how many times during the 1000tosses S9n) will go > >> from a > >> positive balance to a negative balanc eor the other way around. So for > >> our > >> simulation, S(n) is computed by adding one to S(n-1) if a head occurs, > >> and > >> subtracting one form S(n-1) if a tail occurs. A change in sign will occur > >> on > >> the nth toss in one of two ways: S(n-2)=1, S(n-1)=0 and, S(n)= -1 OR > >> S(n-2) > >> = -1, S(n-1)=0 and S(n)=1. This is equivalent to S(n-2)+ S(n-1)+ S(n)=0. > >> so now, n is the numbe rof tosses, S(n) is the number of heads minus the > >> number of tails in n tosses and C is the number of times S(n) changes > >> sign. > >> so we initialize n=0, S(-1)=0, S(0)=0, and C(0)=0 > >> > >> now we should, > >> -generate u, a uniform number, with the increment, n=n+1 ....(our n=1000) > >> -if u<1/2, that is tails occur, set S(n)=S(n-1)-1, and also set > >> S(n)=S(n-1)+1 > >> - If S(n) +S(n-1)+S(n-2)=0, then increment C=C+1. > >> > >> My issue is simulating this in R, where I need to code the number of sign > >> changes, the frequency of heads, and to plot S(n) versus n in a line > >> graph. > >> > >> > >> for each coin toss, the number of sign changes could either be a positive > >> number, zero, or a negative number. > > > > I believe that Jim had the right approach in his reply here: > > > > https://stat.ethz.ch/pipermail/r-help/2007-October/143383.html > > > > and Prof. Koenker has given you a reference on the theory: > > > > https://stat.ethz.ch/pipermail/r-help/2007-October/143385.html > > > > HTH, > > > > Marc > > > > ______________________________________________ > > R-help@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > > > > > -- > View this message in context: > http://www.nabble.com/Need-some-help-tf4624513.html#a13241118 > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >
-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem you are trying to solve? ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
