This is a multi-part message in MIME format. --------------020603020308030506080106 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit
Dr. Rubin: please provide reference to your paper showing the effect of specifying a constant number of "hits" rather than a constant number of point-interceptions. Herman Rubin wrote: >In article <[EMAIL PROTECTED]>, >Jerry Dallal <[EMAIL PROTECTED]> wrote: > > >>Find_Housing wrote: >> >> > > > >>>"David Heiser" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>... >>> >>> > > .................... > > > >>I'm not sure that's your question for a few reasons. Your real question >>seems to be about the actual bacterial concentration level in the bag, >>not that it's 10 or 1000. If it's a liquid and the bacteria don't clump >>(or else see Student's paper on haemacytometers--Bk, 5, 351-360), your >>ability to estimate the concentration will be determined by the >>uncertainty in your measuring instrument, that is, the measuring >>instrument will determine how many samples you need to determine the >>concentration to a particular precision. It would like testing for >>something in your blood. We rarely require a pint because we might miss >>the virus in a particular tube. >> >> > >About 50 years ago, the question came up about estimating the >concentration of bacteria with a given relative error with a >given confidence. The method being used was to count colonies >on a screen. > >In a paper of which I am a coauthor, the simple method was to >count until a given number of particles was observed, instead >of counting a specific amount. This turns out not to be too >difficult; we were told that it is easier than the other. > >Now if instead of estimating, it was desired to test, if at all >possible a sequential procedure should be used. > > --------------020603020308030506080106 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body text="#000000" bgcolor="#ffffff"> Dr. Rubin:<br> <br> please provide reference to your paper showing the effect of specifying a constant number of "hits" rather than a constant number of point-interceptions.<br> <br> Herman Rubin wrote:<br> <blockquote type="cite" cite="[EMAIL PROTECTED]"> <pre wrap="">In article <a class="moz-txt-link-rfc2396E" href="mailto:[EMAIL PROTECTED]"><[EMAIL PROTECTED]></a>, Jerry Dallal <a class="moz-txt-link-rfc2396E" href="mailto:[EMAIL PROTECTED]"><[EMAIL PROTECTED]></a> wrote: </pre> <blockquote type="cite"> <pre wrap="">Find_Housing wrote: </pre> </blockquote> <pre wrap=""><!----> </pre> <blockquote type="cite"> <blockquote type="cite"> <pre wrap="">"David Heiser" <a class="moz-txt-link-rfc2396E" href="mailto:[EMAIL PROTECTED]"><[EMAIL PROTECTED]></a> wrote in message news:<a class="moz-txt-link-rfc2396E" href="mailto:[EMAIL PROTECTED]"><[EMAIL PROTECTED]></a>... </pre> </blockquote> </blockquote> <pre wrap=""><!----> .................... </pre> <blockquote type="cite"> <pre wrap="">I'm not sure that's your question for a few reasons. Your real question seems to be about the actual bacterial concentration level in the bag, not that it's 10 or 1000. If it's a liquid and the bacteria don't clump (or else see Student's paper on haemacytometers--Bk, 5, 351-360), your ability to estimate the concentration will be determined by the uncertainty in your measuring instrument, that is, the measuring instrument will determine how many samples you need to determine the concentration to a particular precision. It would like testing for something in your blood. We rarely require a pint because we might miss the virus in a particular tube. </pre> </blockquote> <pre wrap=""><!----> About 50 years ago, the question came up about estimating the concentration of bacteria with a given relative error with a given confidence. The method being used was to count colonies on a screen. In a paper of which I am a coauthor, the simple method was to count until a given number of particles was observed, instead of counting a specific amount. This turns out not to be too difficult; we were told that it is easier than the other. Now if instead of estimating, it was desired to test, if at all possible a sequential procedure should be used. </pre> </blockquote> </body> </html> --------------020603020308030506080106-- . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
