How Probable is the Most Probable Number

ple decimal dilutions. It is well known that some results occur with relatively great frequency while other results are uncommon. Too frequent occurrence of ordinarily rare results is indicative of some disturbing influence and can be used as a check on technique. 2. To determine confidence limits for use in connection with MPN estimates obtained from a five-tube test using one dilution (as is standard practice on finished drinking waters) and on three-tube and five-tube tests in multiple decimal dilutions. These three types of tests are by far the most comon ones from which MPN estimates are made.