```Date: Mon, 12 Jul 2004 16:12:12 -0700 Reply-To: Marky Sender: "SAS(r) Discussion" From: Marky Organization: http://groups.google.com Subject: Re: NEED HELP in double summing of cross multiplication..PLS!!! Content-Type: text/plain; charset=ISO-8859-1 Hi Puddin' I want to do exactly what you mentioned - I want to compute daily volatility from intradaily data(tick data). So that to obtain good estimates of realized volatility ('good' means that a mean of cross-muliplications has to be as small as possible) I need to choose best (equidistant) time interval and criteria is those cross-muliplications have to be small. Hope I made it more clear. Cheers, Marek pudding_man@MAIL.COM (pudding man) wrote in message news:<20040712010311.784D979002E@ws1-14.us4.outblaze.com>... > 'Scuse me for barging in ... > > Like Howard, I didn't fully grasp your problem (still > don't). You have intra-day returns on traded equity > securities? Are you trying to derive daily returns > from the intra-day returns? It may be beneficial to > further explain what you're trying to do. > > As to the mechanics of what you ask, it is less > problematical. > > Suppose that a trading day consisted of 5 hours, > a measurement being made at the end of each hour. > The following tested code may suggest an approach: > > data ee; > do day = 1 to 2; > do hour = 1 to 5; > x + 1; > output; > end; > end; > run; > > data ff(keep = day hour xday); > array xx(999); > > do i = 1 by 1 until (last.day); > set ee; by day; > xx(i) = x; > end; > > do j = 1 to i - 1; > do k = j + 1 to i; > xday = sum(xday, xx(j) * xx(k)); > end; > end; > > put day= hour= xday=; > run; > > > Hope it hep's ... > > Cheers, > Puddin' > > ******************************************************* > ***** Puddin' Man **** Pudding_Man-at-mail.com ******** > *******************************************************; > > ----- Original Message ----- > From: Marky > Date: Sun, 11 Jul 2004 14:56:59 -0700 > To: SAS-L@LISTSERV.UGA.EDU > Subject: Re: NEED HELP in double summing of cross multiplication..PLS!!! > > Ok- here is example let's assume that 1 day is divided into 5 > observations,so daily cross-multiplications are: > > Observations: Output : > x > 1 1*2 + 1*3 + 1*4 + 1*5 + > 2 2*3 + 2*4 + 2*5 + > 3 3*4 + 3*5 + > 4 4*5 = > 5 = 85 > 6 6*7 + 6*8 + 6*9 + 6*10 + > 7 7*8 + 7*9 + 7*10 + > 8 8*9 + 8*10 + > 9 9*10 = > 10 =635 > > and so on. > > > > Howard_Schreier@ITA.DOC.GOV (Howard Schreier) wrote in message news:<200407110317.i6B3Hd214519@listserv.cc.uga.edu>... > > So you have about 350 trading days (350 x 72 = 25,200). > > > > Why don't you post a mini example (perhaps 2 days x 4 intervals per day) > > and show both the input data and expected results? > > > > On Sat, 10 Jul 2004 11:28:26 -0700, Marky wrote: > > > > >Hi Fellows, > > > > > >I have a problem with following matter: > > > > > >I have about 25000 observations which are 5-minute returns of certain > > >equity (equivalent to 1.5 year). I need to create a formula that > > >computes a sum of cross multiplications every 72 (here 72 equals 1 > > >day)observations. Formula is as follows: (sum from i=1 to 71)(sum from > > >j=i+1 to 72) r(i)*r(j) > > > > > >where r(i) is return in time i > > > > > >PLEASE help me with that. I only made a formula that computes sum of > > >multiplication over all observations, but it is useless for me ;( > > > > > >THANKS for help ```

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